If you don't need a tour you created previously, you can easily delete it.
To delete a tour:
1) Log in to your Roundme account;
2) Find the tour you would like to delete;
3) Click the options button next to the tour preview;
4) Click 'Delete tour':
5) Click the 'Delete' button to delete the tour and all the panoramas it contains.
Please note that once deleted your Roundme tour can't be recovered.