Within Teamwork Projects, you can delete a company in your site for any reason if you have the permissions to do so.
To do this, select the 'People' tab to the top of the page:
In the People area, select the Companies tab to view the list of companies currently on your site:
Select the company you would like to delete, to view the company profile.
In the top right of the screen, click the options (three dots) button, and choose 'Delete this Company':
Note: If there are any people in the company when you delete it, they will also be deleted.
If you would like to delete a number of people from your site quickly, you can move them all to a new temporary company and then delete it.
For more information, see: Working with the Companies view