Bookers can add or remove people from a gig.
If you add someone to a gig, Gixtra notifies them. If you remove someone from a gig, Gixtra notifies them that they were removed. After that, they no longer receive updates about later changes to that gig.
Removing someone from a gig does not remove them from the band. Removing someone from the band does not erase existing gig history.