According to the documentation on this page, if you create an “offer” to be used to add transactions in Ontraport, “there is no way to edit or remove it later”. However, there is a way to remove offers using the live Ontraport API page.
1) Find the “Offers” endpoint on the Live API page.
2) Open the GET/Offers (“This will get a list of Offers”) section and click the “Try it out!” button.
3) In the list of offers it shows, find the “id” of the offer you want to get rid of.
4) Open the PUT/Offers (“This will update an Offer’s data”) section and put that id into the “id” field and select 0 for the “public” field; then click the “Try it out!” button.
This offer will no longer appear in the list of offers when you add transactions in a contact’s record in the Ontraport app.