Removing a keystone jack from the wall plate
Yes.  It is possible.

Keystone jacks almost always have two angled ledges.  One stationary upon which the keystone pivots (Red below), and the other spring loaded which 'snaps' into place (Green below).

Jam a straight blade in at the blue angle to push the green tab in, and pry it out.

In 3by1 and 3by2 outlet plates, it's normal that they are too close together to take out in any old order.  You have to start from one end and work to the other of the plate.