Hi,

After you transformed a VM into a template, your only options are as follows.

I suggest that, making a VM into a template should not an irreversible process.

The normal solution to making your template back into a VM.
Is make a full clone, and the only thing that changed is the VM number.

But also, it seems that really needs to be done is to
1. make sure you don't have any linked clones of that template (does it matter ? do LVM snapshot really consider the original "special" ?)
2. remove template: 1 from the config file

So really the UI could have Convert to VM, check for absence of linked VM (if really needed) and change the setting.