Here is how I achieved it: 

Navigate to Workflow > Workflow editor

Select Published and then search for "Service Catalog Request" 

Go to Workflow actions and select "Checkout" the workflow so you can edit it and click on Set Values Automatic approval 

Remove the Set values > Additional comments "Request automatically approved for total price <= $1000" and click update and set the Workflow to Published. 

Request automatically approved for total price <= $1000 now no longer appears on the portal after a request is submitted.