If you have irrelevant roles within your work templates, you can remove them by deleting the estimates assigned to them within the 'Time & Budget' tab of that template.
To do this, open the preferred template and navigate to the Time & Budget tab. Scroll down until you see the 'Budgets by Role' option.
Select the role and estimate you would like removed, a pop-up will appear with the information for this role. At the bottom left corner of that pop-up, there will be the option to delete the estimate.
This will then be deleted from the budget in the template.
Once you've updated your template, be sure to re-publish to affect changes to all work items created off the template moving forward.