Attempting to remove the final license within an active group is failing with the following error;
"failed to remove license: 'cannot delete last license from active group=<license group>, please switch active group and try again'"
You must first switch groups before removing the last license, in the below example we are using the 'Free' license group.
Via the GUI;
Settings > Licensing > Change license group > Free license (save and 'restart now')
Or via the CLI;
$SPLUNK_HOME/bin/splunk edit licenser-groups Free -is_active 1 $SPLUNK_HOME/bin/splunk restart
Once splunkd restarts, re-run the license removal operation, first running 'list licenses' to confirm the correct hash for the license to be removed;
$SPLUNK_HOME/bin/splunk list licenses $SPLUNK_HOME/bin/splunk remove licenses <hash>
Subsequently installing a new license will automatically switch to, and make active, the group appropriate to the type of license installed (Enterprise, DevTest, etc) following a restart of splunkd.
Add the new license using the GUI;
Settings > Licensing > Add license > <select license>
Or add the new license using the CLI;
$SPLUNK_HOME/bin/splunk add licenses <path_to_license> $SPLUNK_HOME/bin/splunk restart