Ticket History doesn't retroactively adjust. While it's generally not recommended to directly manipulate the database, this may be a case to do it. Be very careful how/if you change the data. The % character is a wildcard (using LIKE) in MySQL
http://dev.mysql.com/doc/refman/5.7/en/string-comparison-functions.html
Make sure you have a verified, recoverable backup of your database. Your data is your responsibility.
A sample query (untested. Use at your own risk:)
UPDATE ticket_history SET name = REPLACE(name, '%%%closed', '%%closed') WHERE history_type_id=27 and name LIKE '%\%\%\%closed%'
Reference:
http://stackoverflow.com/questions/5956993/mysql-string-replace
Please be careful of your data. Understand the consequences of making the changes and, if possible, test in a different environment before applying to production.
It is good practice to attempt a SELECT prior to UPDATE to confirm the change will apply only to the records you want to change.