My question to you is "how fast do you need to go?" The big chain ring is for going down hill at 25-40 mph, which is absurdly dangerous. ( been there- done that )You can loose that ring and be safer for it. The small ring is for going up steep hills and you ride on the flat so you don't need that one either. If you use only the middle ring with an 8 speed cassette out back you won't have any trouble with your chain line and you will have 8 usable gears which should be fine for most sensible riding. If you are absolutely clueless about bikes you can have your local bike shop or co op take the crank off and remove the rings and front derailleur.

I have a n old Peugeot road bike that I set up as a 1x7 with a 36 tooth front ring and a 13-28, 7 speed Hyperglide freewheel in back shifted by a nice Suntour friction thumbie and I live in the hills. My 73 year old legs are not quite as strong as they were when I was 18 but I still manage fine with this set up. If you can do your own wrenching you should be able to do this for $ 00. or maybe the cost of a chainring (used at the co op?) If you want to get fancy , buy another used ring slightly larger that your new middle ring and grind the teeth off it and re install it where the old outer ring used to be .This will keep the chain from ever hopping off the chainring and it looks kool to.