How to Disable new project creation by admin accounts

Hello folks,
we are under some maintenance and migration process, we have two gitlab servers
one with 8.0.3 and other with 10.5.4, being a very big team which works in shifts need to ensure no new project is being created on old server to keep it out of trouble,

We want to disable any new project creation by any user including Admin. on old server (gitlab 8.0.3)

searched google didn’t found any thing other than limiting number of projects for user, wanted to know if there is any possible way to do this.

regards