If I disconnect a card or acct link will it delete all the receipt pics associated with it.
No, if you disconnect a bank account connection, none of the attached transactions will be deleted. If anything needs to be deleted afterwards, they'll have to be cleared manually.
In your case, no, it will not delete your receipts once your bank is disconnected. The receipts are connected to your Wave account not your bank.
Let me know if you have any other questions!