If you are registered to collect GST/HST, you need to prepare a separate GST/HST return, where you report all the sales tax collected, and then recover the GST/HST you paid by claiming input tax credits (ITCs). This CRA website has more info on submitting a GST/HST return: https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/complete-f...
