Activity Streams Error

[CherryGirl69]

I created an activity stream called New Content and clicked Topics only. When I press it it uses the URL http://www.seaselect.com/index.php?/discover/7/ to go to the activity. This worked. THEN;- 

I have just moved a couple of forums and made 2 more unseen by everybody and the URL gives error 

Fatal error: Call to a member function streamSeparator() on null in /home3/cherry/public_html/system/Theme/Theme.php(757) : eval()'d code on line 2242

I then created a new activity stream called New Content 1, this time it uses URL http://www.seaselect.com/index.php?/discover/9/ and works ok.

How do I edit my Custom streams to delete the one that does not work?

Thank you