Making adjustments to Undeposited funds

[Jon12345]

I'm trying to clean up my accounts, having used Quickbooks for about 14 years. I notice I made some mistakes from years ago, where I have undeposited funds that have been deposited. i.e. they are duplicates. They have erroniously gone through onto my P&L and so I paid too much tax.

All I want to do now is reduce the value of the Undeposited funds account to zero, but without it affecting previous years P&L statements just in case I get an inspection. How do I do this?

Thanks,

Jon