You'll want to go to your computer documents and delete the company file from there. Here's how to do it:
If you're using Windows XP follow this given path: C:\Documents and Settings\All Users\Documents\Intuit\QuickBooks Point of Sale x.x\ (x.x is your POS version)
For Windows 7 or Vista, follow this given path: C:\Users\Public\Documents\Intuit\QuickBooks Point of Sale x.x\.
Your data will be in the subfolder and the different folder in it with the company file name. Delete the QuickBooks Point of Sale folder. All the company data files will be deleted. In case if the backup is not in the system, find out the files named as “.qbp”. If the search result shows up, delete them.
Then, go to the recycle bin and empty it completely. Now all the Point Of Sale (POS) data and backups of the organization have been deleted from the system completely.
You can also visit our Help articles page for QuickBooks Point of Sale and learn some tips in managing your account effectively.
Let me know if you have other questions. I'm always here to answer them. Have a great day and take care!