Restore the template file.

[Grafidea]

After restoring the template file to the default it still shows that it is modified although it is not because it has been restored to the default value.

[Makoto]

When you hit "Revert", don't hit save again.

Reverting automatically saves it in its default state, hitting save again after that marks it as modified even when the contents are identical.

[Marc]

Please could you confirm the above is what you are doing there? Makoto is indeed correct. Please confirm if this is not the case and let us know which template