You can the edit the tags of an activity or an activity entry to modify them. You can also add and remove tags.
Owners can edit all tags, both activity tags and entry tags; Authors
can only edit entry tags, and only those associated with entries that they
authored.
You can modify tags to make them more consistent with other tags.
For example, if you use the tag report for some entries
in an activity, but you use the plural form, reports for
other entries in the activity, you might want to remove the s from
the second variation so that all of your tags are consistent.