Hi Megha,
There are a lot of creative solutions to come up with. Probably even better than my following suggestion. What you can do is adding 2 helpers, first a list of the same type as A, named in my case "ListAList_ToRemove", second an extra boolean variable which you create on your listA iterator named "found". You set the default value of found to false, if you iterate trough list B you can change the value to true when it matches. Then after the loop of list b you check if the value of your variable is still false, if so you add it to a list to remove. After looping trough all items of list A you change your list A and remove all items at once with the created "ListAList_ToRemove":
And a modelshare of my microflow setup, note that it is created in 7.18.1:
https://modelshare.mendix.com/models/f4ff3625-06a0-46b8-9611-818061687872/extract-values-from-list
Hope this helps you on the way!
Kind Regards,