Thank all...
Delete Forum Image: OK
Add Forum Image: OK

Server Information
UBB.threads Version 7.7.1
Release 20190129
Server Type WINNT (WIN10)
Web Server Apache/2.4.39 (no set cache) in 127.0.0.1 test
PHP Version 7.3.4
MySQL Version 8.0.15
Database Size 492.48 KB

but Update/Remove Forum...
i see /images/forumimages/default new images file
in wed no see...