I had previously been using InDesign for work, which I no longer have need of. Photoshop fits my design needs better. I need assistance switching my single application subscription from InDesign to Photoshop, but do not want to pay a cancellation fee. How do I proceed?
As I read, you wish to know if you can change the plan or not, you can definitely change your plan from Single-app Indesign to Single-app Photoshop or the Photography plan(Photoshop+Lightroom/ $9.99 a month).
You may please see: Manage your Creative Cloud membership
For more details Contact Customer Care
Hope that helps.
Feel free to update the thread for any other information.