You do realize that Obama has tried to find several ways to do this, and has been shut down by the Republicans every time?

Congress ultimately decided to keep Guantanamo, and left zero room to find a single solution; Obama had no choice but to negotiate transfers with other countries (a long and problematic process) while at the same time let the court system handle the remaining cases. Obama could perhaps have tried harder, but he has had a lot of resistance on many fronts from the GOP.

He has almost succeeded at this point, anyway; there are only about 40 prisoners left. [1]

[1] https://www.washingtonpost.com/world/national-security/with-...