For Business and Enterprise users, you can turn access to a project on for everyone in your GLIDR organization - or off so you might select which users have access to a project. 

In Project Settings > General for a project, scroll down to Project Access. Toggle Limited Access on if you'd like to choose which users have access, or toggle it to Open Access to allow anyone in your organization to access and work in the project. Please note organization-level Owners and Admins will have access regardless.

This affects Enterprise and Business tiers of GLIDR; in Starter and Team, all users have access to all projects.