Data filters for views
Instructions for creating filters are in Create/manage view filters.
To filter out a referring source from your reports, create the following filter:
Filter Type: Custom Filter > Exclude
Filter Field: Campaign Source
Filter Pattern: Enter the domain of the referring source that you would like to exclude, for example, google.co.uk. You can use regular expressions if you would like to exclude several referring sources.
For an overview of filters, read About view filters.