Wanting to close an underlying IR claim

I am on CB ESA. It was recently brought to my attention that I had an underlying IR Claim that I had not received any money from for 8 years.

I wrote to the DWP and asked them to close this underlying IR claim and just keep the CB ESA award open as my savings are well above £16 000. Instead they wrote to me asking for bank statements and said they needed to review my capital. I had no choice but to send the statements.

I know someone else in this situation who now has to send bank statements every year as well as receipts for everything over £250 he has bought so the DWP can monitor how he is spending his money, in case he ever wants to receive IR ESA in the future.

I’m not intending to ask for any IR ESA in the near future. Am I allowed to close the IR claim and just keep the CB ESA claim open? How would I go about this? Writing and asking clearly did not work. Possibly I did not word the letter correctly.

If I do manage to close it and did need to reopen it in many years time eg 8 years, would this be an option? I’m hoping I will never need to reopen it but I do not understand the rules at all.