You can probably choke it to death.
But brakes . . . get something that will stop you. Or the lack thereof will cause unrequited grief for family members, whether getting you flowers in the hospital or putting flowers on your grave.
I'm not trying to rain on your parade but if I understand you your bike has no brakes at all.
You won't find one member of this forum (I hope) that will condone riding it without brakes. Not even a test ride.
What size rear wheel do you need? Post your wheel size and zip code. I should have a coaster wheel around somewhere. I'll true it and send it to you if you pay shipping.
Otherwise see if your LBS will put your original coaster hub on your new wheel. Tell them you will remove the hubs from your wheels - cheaper that way. So you will just pay them to build your wheel with your parts.
You can't put your original wheel back on? Is it damaged in some way or did you just want a freewheel (BMX) rear?