"I have made the difficult decision to opt out of this season to focus all of my energies on some personal issues," the 22-year-old said.
It's not clear if De Sousa is departing the program outright.
Jayhawks coach Bill Self said the forward was not on the same page as the basketball team during recent workouts.
"Knowing Silvio, it was clear he had been distracted and not fully focused during workouts as of late," Self said, according to KUSports.com's Matt Tait. "After he and I sat down and talked about that, it was clear this was the best decision for him and Kansas basketball, to leave the program. At some point in the future, Silvio will decide what his next steps will be and where that will take him."
De Sousa was suspended for 12 games for his involvement in a Jan. 21 brawl during a matchup against Kansas State. He was eligible to return to action in March but never did before the coronavirus pandemic hit.
The Angola native was ruled ineligible to play in 2018-19 due to his connection with the NCAA corruption scandal. De Sousa averaged 3.3 points and 3.3 rebounds in 38 total games with Kansas.