Users can not be deleted in SOMAX but they can be inactivated. Inactivating a user will remove the user from all Assignment Search and Lookup lists. Additionally, if the user was a full user type then inactivating will "open" a full user license.
To Inactivate a User follow these steps:
Click| User Management
Click on the User Name you wish to Inactivate
Uncheck the for Is Active
Click Save