@FranzP @Netlify There isn't currently a way for you to force a deploy to quit. Builds timeout after 15 minutes, but I'm afraid, right now, you have to wait for that to happen if they get stuck.
We do try to make it easier to spot (and fix) lingering processes:
https://www.netlify.com/blog/2018/11/28/fearless-deploys-for-your-lingering-processes/