This idea has been implemented in ZENworks 2020. A new setting is available (at zone level, Bundle folder level, bundle level) which would determine how many versions of bundle are retained. www.novell.com/.../t4al753ajybh.html
I did vote for ideas.microfocus.com/.../1864 as well. The focus on that idea is to automate and keep X number of versions. I do like the option of not having to use an automated process and being able to just do a mass cleanup of bundle versions keeping X number of versions. Perhaps this can be implemented on the Bundles tab where I can select all bundles, or selectively choose bundles to purge bundle versions keeping X number of versions.
Bit clunky to use but I've used the Novell's ZENmigration tool configured to look at the Migration Destination (doesn't need a Source).
This way able to select multiple bundles that exist within a zenworks folder. Need to make sure you only select those bundles with @Version in name.