For some opportunities, the buyer may require you to submit an Intent to Bid which will look like the following: 

If you've already submitted your Intent to Bid but you no longer wish to bid, you can go back to the opportunity page, and change your answer from Yes to No OR vice versa.

NOTE: You will not be able to change your answer if the Intent to Bid deadline has passed. The idea behind declaring your Intent to Bid is to allow the organization running the bid to get a rough idea of how many submissions may be coming in. If you have not submitted your Intent to Bid by the deadline you will not be able to prepare a submission. In this case, you will want to reach out to the Project Owner to inquire how you should proceed.