How to edit Custom Tags:
It is not possible to delete either a system tag or a custom tag once you have created it. However, you can edit the name of a custom tag and change the tag's location in the tagging hierarchy.
On the full desktop version
Go to Account Settings (profile icon, top right) > Manage Tags
Firstly please note it is not possible to rename or reorder the main system generated tags, only user-created custom tags. Tags you have created yourself can be identified by the star icon to the left of the tag name.
To edit the tag name click on the tag and amend the name in the field then click/tap Done. To move a tag click on it then drag and drop onto the Top Level or Sub-Level tag list you want it to appear under. Eg, a custom tag for Movies that is incorrectly appearing under Insurance can be dragged onto Enjoyment > Entertainment/TV/Media where it would be more appropriately located.
If you have a tag that you can't rename to anything you would want to apply to one of your transactions, then in the meantime you can always set up a new Top Level tagging category with an arbitrary title (eg - 'Unused tags'), and drag and drop all your unwanted custom tags to be housed there.
On iOS/Android Apps
It is not currently possible to reorder a tag's location in the tagging hierarchy from the mobile apps, but you can still amend the names of Custom Tags.
To do this go to the Transactions screen and tap on the 3 line icon, then select Manage Tags. Here you can see a list of all the Custom tags you have created and tap on any tag to amend the name.