There are two options.
1. Delete inquiries on the Inquiry List Page
On the Inquiry list page (CLICK HERE), you can turn on a column called Delete which will give you a delete button on each inquiry row in the list. Simply click on the cogwheel in the top right to open the column setting and click the tick box next to the Delete columns.
Drag and drop the delete column to wherever you want it, and then you can delete inquiries directly from the inquiries view.
2. Delete an Inquiry in Contact view
You can also delete an inquiry by clicking into the Contact profile of the person. In the list of Inquiries on the Contact profile, you'll see a delete icon next to each inquiry on the right-hand side.
If the Inquiry has been converted to a booking, you'll need to delete the associated booking first as it is linked to the converted Inquiry.