Flashing stock recovery back

Hi, I have a friends HTC One M8 who rooted it and added TWRP recovery and is S-on.

The phone is on the original HTC software version 4.19.61.2 and I have found the stock recovery for this. the phone has never had any other roms installed.

He wants to get the OTA updates and just need to know if it is ok to flash the stock recovery back without any problems.

After flashing the recovery if this is ok, is there anything else we would have to do to get the OTA upates.

Thanks in advance

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