Currently it is not possible to cancel ongoing builds, even if you know they will fail.
You have to wait for the buildsystem to fail. This is annoying if the package takes long to build.

The only way to "resubmit" is to increase the release counter. Which will result in concurrent builds of the same package, one to fail and the other one (to hopefully) succeed. This is just a bad workaround.

It would really help if we get an option to cancel on ongoing build - even if it is a bad hack, like removing the build dir which will result in a failure and then cancel the build.