How to remove a user's ability to create new sites?

Chatter groups becomes Simpplr sites. You will need to remove user's “Create and Own New Chatter Groups” permission in their Salesforce profile to remove their ability to create Simpplr sites.

1. Login to Salesforce, go to "Setup".  Go to "Administration Setup"  > "Manage Users" > "Profiles" and click on the profile used by the users. 

2. Click "Edit". Scroll down to "Administrative Permission" and uncheck the box next to “Create and Own New Chatter Groups”, then click "Save".