After completing a monolith mission, there doesn’t appear to be any way in game to move to another area. I would suggest adding a waypoint to this zone, just like every other zone.
One work around is to log out and log back in again as this transports you back to the End of Time hub but this can be tedious especially if you’re playing a summoner. since all your summons disappear when logging out. This issue is even worse if you like to use rare summons like flame wraiths for example.