Hello

I believe that there are two ways without having to do anything too involved yourself:

1 - use a batch update JNCCDel5Records.xml
If it is available, right click on the survey you want to delete, select Batch Update from the Context Menu, followed by Delete > JNCCDel5Records (this might depend on your set up to some extent). On our networked installation the report lives in
Recorder 6 Server\User Files\Batch Updates
This batch update deletes everything down from a selected level, including Surveys.

2 - install add-in SurveyDelete.ocx
I inherited this add-in with our installation, so I don't know where it came from or is still available to download - couldn't see it here: http://jncc.defra.gov.uk/page-4597.  We've got v.6.0.0.25 2009 by Stuart Ball.
I've never used it myself, but it adds a delete survey option to the Tools menu, and looking at the Read Me seem that you can empty a survey of records as well as delete the whole thing including records.

Generally with this type of operation you need to close the Survey Hierarchy window and re-open to see effects. Obviously use with caution!

Best,

Andy.