You need to post your code snippet like I have and not provide a screenshot image of your code attempt. I have updated the code example to just show the volume of a closed trade instead. I was expecting your attempt at detecting a partial close of the volume. Please can you do this first?
Please read the guidelines again for the type of help we offer, you need to provide your code attempt at the solution.
https://ctrader.info/d/14-ctrader-cbot-coding-help
Possible Solution
There is no single method or property that will tell you if a position is a partial close, you will need to add the logic yourself, one possible solution is to get the volume of the closed trade and compare this against the original volume.
If you attempt to code this I may be able to help you.