Removing a simulation in the editor

First close the engine and open the project in your file explorer. Go to the "Content" folder of your project and head to the directory where you store your simulation files. In the directory of the simulation you want to remove, delete all directories, but do not delete the "SI_[CHID].uasset" and "[CHID].uasset" files!
After doing so, you reopen the engine again and now delete the simulation info "SI_[CHID]" and simulation asset "[CHID]" file in the editor to check for any dependencies that will be broken by removing these simulation files. If you still have dependencies, you get the option to either replace the references by another simulation or force-deleting the references. Both works fine here, choose as you wish.

Please note: When you are not using the editor, you can safely remove all files in the file explorer. However, if you have ever used the simulation in the editor, make sure to follow the steps above.