At any time, you can renegotiate commission on a product. You can do this by clicking My Suppliers under the Suppliers tab > select the supplier from your My Suppliers list on the right side.
Scroll down to Products > select the product/s you want to renegotiate > click the Actions button > Propose new terms. This will take you to a new page where you can modify your commission.
Enter your proposed commission and it will automatically update the product pricing as seen below.
Update the table with your requested commissions and you'll be required to add a message before sending it to the Supplier. Like a normal proposal Suppliers can approve, decline, or counter. While the renegotiation is pending you will see a clock icon next to the commission in the Inventory and Approved tabs. This designates that a commission is being renegotiated. Until the new commission is approved, the previous commission will apply to any sales.