Click on 'Settings' at the top of the screen, then the 'Tags' tab. Select the tag you want to change. You can then either click on 'Delete' to remove it, or click on the pencil image by its name and rename it.

Tip: Sometimes when you delete a tag is will still show in the list on a mobile device. You may need to delete it separately on those devices.

Can you explain exactly how to delete the tag from mobile devices? When I long press on the tag, my only choice is "Edit Tag". When I select "Edit Tag", my only buttons are "Save" and "Cancel".

A coule of things, Tag will still show in the list when doing Smart Add while tasks exist (even completed ones) with that tag. If you go and delete the completed tasks and there are no uncompleted ones with that tag then the tag will vanish.

On the app for Android, you have to delete them on the device - that doesn't sync with the site (annoyingly) and it's not exactly intuitive how to do it! You were almost there, there was one more step to go.

Go to Home
Go to Tags
Long press a tag and choose Edit Tag
Press your phone's Menu button and Delete Tag will pop up at the bottom of the screen.

Hi morefun2compute,
Once you've tapped on "Edit Tag", press the Menu button to show the "Delete tag" option.

Hope this helps!

Cool. Thanks. Yeah, once I deleted all my completed tasks, the tags immediately disappeared from all my mobile devices.