I've been trying to recover some disk space on my TC server but the cleanup task is not cleaning up the artifacts I expect it to.
My rules are set that artifacts older than the 5th build should be cleaned (pattern is +:**/*).
Some artrifacts have been cleaned correctly but fewer than I expected.
I increased the logging for the CLEANUP process to DEBUG and noticed the following in the cleanup log file:
DEBUG - jetbrains.buildServer.CLEANUP -The following builds cannot be cleaned: [17600, 15301, 15302, ...]
DEBUG - jetbrains.buildServer.CLEANUP - These builds are referenced from: 
Unfortunately there is no more information in the logs, and the builds listed are exactly the ones that are using the most disk space.
Can I safely manually delete the folders that correspond to the builds listed in the log message?