is there any way to completely remove/disable gust access?

i work in a secure environment and can have nothing on the network that allows guest access. 

Set the security on the shares to be either Secure or Private.   When you go that way you have to set up users and specify for each share what type of access the users are allowed to have.   There is, unfortunately, no support for groups in Unraid so each user has to be done individually.