Sure you can, see if you look at the picture, the only thing your megaflow is doing is silencing the gurlge noise that comes from the water rushing down the pipe. you can pull it out right now, no joke. it will just be louder, like a toilet flushing. The thing that holds all your water is the overflow. The pipe is just a silencer. Also known as a Durso Standpipe.
Do you have the return pump plumbed up and everything? The only thing I would check on is that your sump can hold all the water that will slowly trickle into your sump in the event the return pump goes out. You can check this by removing the standpipe and letting all the water IN the overflow go to your sump. If it holds, your all good!