Hello and welcome to Justanswer!
The transfer case on your Jeep is manually controlled through the shift lever on the floor. Moving the lever moves linkage which moves an arm on the side of the transfer case.
Since it is mechanically controlled and the same parts inside are used for full time operation and four low, even if the transfer case was disassembled there isn't anything you can remove to disable part time four wheel drive and still retain the other modes.
If it's getting stuck in four wheel drive it could be a couple things.
It could be an internal failure in the transfer case. This doesn't happen that often but is possible.
More often it is caused by a tire issue. If there is a difference in tire circumference then it will have a hard time coming out. Take a look at the tires and make sure they are all the same size, brand, and of the same tread wear. If any tire is a different size, underinflated, a different brand, different tread wear amount, or the spare is in place then it will cause this. Often someone will replace one or two tires at a time and that can't be done on a four wheel drive vehicle, if there is any difference in wear it causes transfer case issues, all four tires need to be replaced as a set to avoid problems.