How i can choose the api's inside the collection for running in Collection Runner

My collection consists of 50 apis in total.I am using data from the external .json file
While running in iterations, my total no of iterations is 8.

I want the first iteration to pick 10 apis only rest ignored.
second iteration to pick next 5 apis only.

Need for the above approach is that scope of 1rst , 2nd iterations is for that api’s only.

Is there a reason for not running them as separate collections sequentially?
You can use iteration as check for flow control and make your collection quite fragile.
are your tests separated in folders already or are they just in a long chain?

The api’s are separated by folders in the collection.

Why run them all together as a single run ? Seems like 35 APIs are always called along with 5 or 10, so why not 3 runs? Or 2 runs with 49 and 45 requests respectively? Sound like you want to do everything at once which will give you maintenance issuea