[filburt1]

I think you need quotes...or if you don't you probably should anyway:
[sql]
DELETE FROM template WHERE template LIKE "prefix%"
[/sql]
For example:

mysql> select userid,username from user where username like "filburt%";
+--------+----------+
| userid | username |
+--------+----------+
|      1 | filburt1 |
+--------+----------+
1 row in set (0.00 sec)