DataBinding Question and Implementation

I am use to pointers and can delete any record very easily. I current switched to C# and I am using a DataTable to bind to a grid. The issue is that I know you can use at indexof to remove the item from the data table. The index changes as items are deleted so this will not work for multiple rows. I hate to use linq or a for statement to loop through the entire datable to delete just one item. There has to be a way if I have a unique key that I can find and remove that item from the data table without some kind of looping. IDictonary might be another solution. I don't care I just have to be able to easily delete one item at a time. These datatables can have 300K records or more in them. I will listen to any suggestions and I want to keep the overhead as low as possible as these are huge applications.