Remove Column value based on selected 'Effective Date'

Hi,

I have two tables, including Table 1 and Table 2 as attached.
Below is an inquiry but could not get answer. Hence, I ask for the same question here. 

https://www.excelforum.com/excel-programming-vba-macros/1409935-remove-column-value-based-on-selected-effective-date.html 

Now, when the same part number is in need of price update, the month total price (wrt quantity) shall be updated in associated with 'Effective Date'

For Example, if Part number 'AAA' is added on Nov 2023 (202311) (in Row 6) with price different to pre-existing 'AAA' , the pre-existing row of 'AAA' (in Row 2) shall be updated in a way that the month total price after 202311 becomes zero; whereas AAA in Row 6 shall be calculated only after 202311.

Please advise how it can be done.