Uninstall older/unused versions of candidate

[xeruf]

Please tick one:

• this is a new Feature Request, a conversation was started in the Gitter CLI Development Room.
• this is a new Bug Report or Issue, a conversation was started in Gitter User Issues Room.

Please explain the Issue / Feature Request here:

When using Gradle, I only ever need the latest version, so i would like to request two related features:

1. Allow me to set a flag for a candidate that tells sdkman that this candidate should always be replaced by the new one instead of keeping the older versions.

2. A command to remove all versions of a cnadidate which are not active.

[clehene]

There are two issues.

• One that, on upgrade old versions are retained without limit
• no reasonable way to remove old versions

A garbage collection option would be nice. I'd expect it to work just by manually deleting unwanted versions from a directory directly.
Can someone chime in?