Is it possible to automatically delete executions or not store them at all?

As the title says. We go through a lot of workflow execs but it’s not really necessary to store them.
It’d be even nicer if we could only store the failed executions, but that might be asking for too much

Yes, that is all already possible. You can set the environment variable EXECUTIONS_DATA_SAVE_ON_SUCCESS to none to not save successful executions. You can find the documentation here.

Additionally, can you also tell n8n to delete old executions after a certain amount of time, like one week. You can find the documentation about that here;