Advice on voluntarily stopping mobility payments

Hello there
I wonder if anyone can help?
I currently receive enhanced rate of PIP for both daily living and mobility.
It is due to come under review after three years in March 2021.
Since the initial award I have started to drive again and had a one year medical licence extended to three years.
I want to request that the mobility element is stopped.
I have some concerns over what will happen once I trigger this:
1. Will both elements of the benefit be stopped immediately until it is sorted to the DWPs satisfaction?
2. Does it come under a 'change of circumstance' and if so what does that mean?
3. What form will I be sent to fill out. I have had an 'are there any changes' form previously.

I am worrying about this since I want to do the right thing, but am also worried that having my benefits stopped altogether will mean I won't have enough to live on and that the effect will be to trigger a major episode (type 1 bipolar disorder). I am struggling with everything currently, but feel so worried about this that I want to get it sorted now.

Any information gratefully received, and thankyou for taking the time to read,
D

Thankyou for the helpful response.
I am not well currently, but find the whole mobility award so confusing, I would rather just not have it. I will send a letter and hope the psychiatrist will help me with the fallout. Swapping one worry for another really. Thanks again, D