Why do you want to shrink tempdb in the first place? Shrinking is a very exceptional event. It is only useful if you know why the item you want to shrink got its current size, you have reason to believe that will not happen again. For instance, someone ran something unbelievable silly and tempdb exploded.
But if you don't know why tempdb has its current size, you should assume it is because the workload requires this size. Shrinking the database will own mean that it will grow again, which takes resources.
Also, there is only point in shrinking if you need the disk space for something else. It is not uncommon to have tempdb on a disk on its own. Why would you shrink in that case?
So tell us, how big is your tempdb and why do feel you need to shrink it? And how big is the biggest user database on the instance?