Find can execute arguments with the -exec option for each match it finds. It is a recommended mechanism because you can handle paths with spaces/newlines and other characters in them correctly. You will have to delete the contents of the directory before you can remove the directory itself, so use -r with the rm command to achieve this.
For your example you can issue:
find . -name ".svn" -exec rm -r "{}" \;
You can also tell find to just find directories named .svn by adding a -type d check:
find . -name ".svn" -type d -exec rm -r "{}" \;
Warning Use rm -r with caution it deletes the folder and all its contents.
If you want to delete just empty directories, a way to hack around that is to use rmdir instead of rm -r:
find . -name ".svn" -type d -exec rmdir "{}" \;
This will delete empty directories and give errors for directories with contents. If you do not want to see the errors, redirect the STDERR to /dev/null
find . -name ".svn" -type d -exec rmdir "{}" \; 2> /dev/null
