Cleaning up the build folder for registered and active runners

I have a few questions about build folders and keeping their sizes in check.
Are runners folders or at least “chunked” folders inside of them safe to delete to clean up some space without interfering with the deployment of new releases of production servers that are already deployed by the runners? If not, what is the best way of dealing with increasing size of the build folders without harming the production/deployment?

I’m struggling to find some particular information about the designation of the builds folder and how it works. As I understand it, gitlab-runner executes git clone after picking up the job and build folder is where repository clone is stored. However for every project inside runner’s build folder there is a “chunked” director that contains a bunch of tasks files and they are starting to take too much space.
I am curious of their purpose but more importantly I need know if they are crucial for deployment of the projects and/or for the work of respective runners

Any advice or link to a documentation/explanation of how exactly these files work and how to clean them up would be of great help.