Server closing before I can join

I believe there is a problem regarding some of the mods on my server and I had tested the issue with my friend, and they were able to join without any problems. I tested it again by deleting my player profile in the files of the server and this solved it temporarily, while the server started to act up again just about half an hour later.

Here is the log https://mclo.gs/YrM4tot

I am running the server on Valhelsia 3 from curse forge, and am wondering if it's a problem with some of the mods, and if I need to remove anything or if it's a problem with my player.

How do I select a world solution?

How would I go about removing Alex's mobs because we've been playing for a few months and I wouldn't want to restart our progress in the world?

The newly generated world seemed to work fine even with Alexsmobs still in the server.