basement window question

Have a question about traditional basement windows. I get the idea of how they are supposed to be installed (shimmed even then packed with mortar on the sides and bottom and caulked on the top), but my case is alittle unique. It is an older home with kinda odd windows and opening so it is gonna be kinda hard to get the same size replacement windows (openings are all 32-32 1/2 wide but some are 14 which is common, but some are 14 1/2 and gonna take some filling, and some again are 16" ). Not sure what they were doing but none the less not gonna make it easy not to mention some are put in in a way which they are aren't sealed against the ledger board of the house, and I would like to fix this obviously. It looks like I'm gonna have to get each window out and address each on a case by case basis it looks. My question is about these mortar ramp things on the inside of the window. Maybe not the proper name but here's a pic of what they look like



Do these serve any purpose other than to take up the difference between the window and the block? If I can knock these out and just go with a flat block surface it would make my life alittle easier getting a window in there. I wanted to ask questions being I'm not 100% sure what I'm getting into though. Thanks for your help/ideas.