Several members of the Jedi Order found themselves cut off from the Force following intense trauma, such as Cere Junda and Cal Kestis. Other Jedi like Ahsoka Tano and Luke Skywalker purposefully chose to distance themselves from the Force during periods of self-imposed exile.
Most recently, the book Shadow of the Sith introduced an artifact that forcibly cut Luke off from the sacred energy field. Ultimately, he cut himself because he felt unworthy to be "the chosen one" and because he didn't want to know, or more accurately feel, what was going on in the universe.
In Obi-Wan's situation, it was utterly important to remain hidden, and using the Force can attract other Force users. So, by all appearances, Obi-Wan did what Ahsoka did. He cut himself off from the Force so that he wouldn't jeopardize Luke by alerting Vader or the Inquisitorius to their presence.
In Legends, there was one Jedi who couldn't use the Force. Meet Tionne Solusar. According to Firesetorm, Tionne possessed very little Force powers, in fact, she was barely Force-sensitive.
The Force is a fictional concept in the Star Wars franchise, so it is not something that can be physically cut off from. It is force ability to suppress ones connection to the Force called Sever Force.
Several members of the Jedi Order found themselves cut off from the Force following intense trauma, such as Cere Junda and Cal Kestis. Other Jedi like Ahsoka Tano and Luke Skywalker purposefully chose to distance themselves from the Force during periods of self-imposed exile.
1 Darth Sidious
There has been no Sith, as powerful, meticulous, nor as evil as the Emperor himself, Darth Sidious. As previously mentioned, Sidious trained in the Dark Side by Darth Plagueis before Sidious killed Plagueis in his sleep, making Sidious a Sith Master.
Master Yoda has risen above all others to claim the top spot as the most powerful Jedi of all time and the true chosen one according to IGN's audience. He won pretty handily as well, as he was victorious in 89,756 of his 95,243 battles and had a win percentage of 94.2%.
Jedi Master Yoda is the most powerful of them all. This should come as no surprise, as he was the head of the Jedi Order in the prequels and was revered for his abilities during the original trilogy. Yoda's power is unmatched and was a real threat to Darth Vader and the Imperials.
A key detail proves the body in the Obi-Wan Kenobi Jedi tomb scene isn't Mace Windu — its hand. The body's right hand is visible in the shot. This means it can't be Samuel L. Jackson's Star Wars character since Mace Windu had his severed by Anakin during the fight with Palpatine.
At the time, it's likely Obi-Wan smiled because he was about to become one with the Force, and he was fine with that after seeing Luke, their last hope, make his great escape.
The main reason for this is due to Kenobi's long stint in hiding. Again, Kenobi has been in hiding for around ten years, slowly diminishing his connection to the Force. While the Force, and people's abilities with it, are hard to define in Star Wars, it remains the case that the Force acts as any other skill does.
Because he was shocked to his core. He offered Luke the same thing he offered Padme, a place at his side to rule the galaxy. It was what he himself wanted, to be free of Sidious and rule with his son.
Luke reached the full potential in the genes of the Skywalker bloodline. At full strength, this makes Luke approximately 2 times more powerful than Yoda and even Darth Sidious.
Powers. The Force: As the son of the Chosen One, Anakin Skywalker, he was immensely powerful and had a amazingly strong connection to the Force, stronger than most Force users alive. Like his father, Luke possessed a powerful connection to the Force.
Biography. Legend had it that Yoda—a Jedi who became Grand Master—was trained by N'Kata Del Gormo.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker.
Plo Koon. Wise and compassionate, Plo Koon was one of the most effective Jedi masters, genuinely caring about the clones he commanded.
Unwilling to see his son die, Vader gave his life to save Luke, thereby dying as Anakin Skywalker. Anakin ultimately fulfilled his role as the Chosen One and brought balance to the Force, fulfilling Qui-Gon Jinn's belief in the prophecy that foretold Anakin's destiny.
A Sith Lord with the ability to cheat death and create life, Plagueis is the mentor of Sheev Palpatine / Darth Sidious, who, in accordance to the Sith's Rule of Two, eventually betrays Plagueis by murdering him in his sleep, taking his place as Sith Master.
Truly, the most powerful Sith Lord was Darth Sidious, better known in his public persona of Chancellor (later Emperor) Palpatine. Through cunning and manipulation, Sidious killed his master to claim the mantle of Dark Lord of the Sith.
killed by an Imperial strike team, his dark side, like many Seth before him, refused to let go of life.