In this case , you need to cancel current subscription.
It will be Ideal to subscribe for Creative cloud Photography plan which includes Photoshop , Lightroom and Lightroom Mobile :
It will cost u like $9.99, for more details refer above link
In order to switch the plan, first you will need to cancel your current plan as per the document below:
Once the current plan is cancelled, you may go ahead and subscribe to a different plan as per your requirements.