You should create a separate View for just desktop visits and create two filter to exclude mobile and tablet visits.
Create A New View:
Go to Admin -> View -> Create New View -> Name it - Desktop Only
Create you Filters
1) Go to Admin -> Desktop Only View -> Filters -> New Filter
2) Filter (Exclude Mobile) -> Filter Type: Custom Filter -> Exclude -> Filter Field -> Mobile?
3) Filter (Exclude Tablet) -> Filter Type: Custom Filter -> Exclude -> Filter Field -> Tablet?
This will give you full control of all desktop visits.
Another tip: Always keep a raw view for all your properties. Basically, a view that will never be touched unless you break all your other views. Once you apply filters and other stuff you cant go back and change things for that particular view.