Possible Issue(s)
When typing “</”, the “/” deletes removes the “</” completely
When typing both “/” keys will be ignored completely.
Cause
Tag Package
Solution
Disable the Tag package (Tag package may try to reinstall itself if just deleting the files?)
Preferences > Package Control > Disable Package > Tag
Other
It may have conflicts with other packages?
Search Keywords
close tags, closing tags, closing html tags, close html tags, forward slash key deletes removes opening tag