Here's how you can edit your stations on iPhone:
 
From your Stations list, select the station you'd like to edit. If the station automatically starts playing, tap the back arrow in the upper left hand corner to return to station details.
 
Two options will appear underneath the station name: ‘Add Variety’ and ‘Options’.
 
Tap ‘Add Variety’ to add additional artists or track seeds.
 
Tap ‘Options’, then ‘Station Details’ to view the seeds and thumbed tracks.
 
To delete a seed or thumbed track, swipe your finger across the seed or thumb and a red ‘Delete’ button will appear. Tapping on ‘Delete’ will remove the seed or thumb from your station details.
 
You can also edit stations if you tap and hold the name of the station you would like to edit, then select ‘Station Details’ in the next window.