Not sure what you are after, but.....
Press the "K" key to split the clip. Press the back arrow key to move the marker. Tap the mouse to select the piece under the marker. Press delete.
For me, it is easier to drag the edge of the clip into the marker.
Thanks for the tip, it is an option to what I was asking. The difference is that by deleting the unwanted frames it is difficult to add them again if you change your mind in a later stage of the editing. With the trim option you can just "re-trim" the starting point a bit.
Those features only exist in PrPro.
As mentioned above in this thread, You can press ctrl+k, it will split the clip and then you can delete first part.