If you're still shopping simply click on the Cart Icon in the upper right of the website to modify your order.
If you already submitted your order to Univar you will need to call and speak to your Univar rep or call 800-888-4897 and speak to a rep in your area.
If your account has Order Approvals enabled, you should check to see if your Order is Pending Approval. If so, you can ask your company's Order Approver to modify your order prior to submitting it to Unviar.
Note - Order Approval functionality is not used by all Univar customers.