Synth settler wont leave when sent to another settlement

I have a settler that was switched by a synth. Settlement happiness is dropping to extremely low numbers.

I go to Workshop Mode to sejd him to another settlement but he won't leave.

I want to kill this particular synth but he just won't leave and another settler always seems to be by his side at all times so if I shoot, the entire settlement becomes hostile

I did a quicksave and he is the only synth there

Any tips on what is happening and how to solve it (PS4 without using mods/console commands)