The root problem is that you have multiple developers working in a single org (and even worse, doing so via Developer Console). This is not a recommended practice and can lead to lots of challenges, including overwriting one another's changes and other species of mutual interference.
There are a wide variety of development operations that can cause different portions of an organization's setup to be locked while they complete. (See this article for a partial list; note that deployments can also cause setup locks, and saving a class in Developer Console is a deployment). You can't turn off or manipulate these locks per se, although you can try to understand what causes them and alter your processes to reduce their impact - for example, scheduling much smaller test runs, or choosing when to run tests.
The best solution, though, is to stop sharing orgs for development. Use multiple Developer Editions or Developer sandboxes, or best of all use scratch orgs. Practice source control, and use a proper IDE, not Developer Console.