I'm new to biking only doing it since the past 3 months. I don't use my front gears much since i'm pretty tall and lower gears means going at a very high cadence for little output. so wondering if i could remove the derailleur. Does this create any problem?
I would fix the derailleur on the gear you prefer (perhaps middle one, to get most of rear gear properly working) as the derailleur don't interfere to leg movement. Take in mind that in few months you can change your mind and start using front gears too.
Edit: To remove it you will have to unbar the chain, then open the screw (9mm wrench or 4mm alem depends on derailleur model) on other side of the derailleur. Then return the chain to place.
As others have said, sure, it can be removed, but let's look at the pros and cons.
- A trivial weight reduction
- You lose a whole range of gears intended for climbing
- You lower the bike's resale value
You could reduce weight even more by simply losing a few grams of weight yourself. So unless you live in a place with no significant hills and never plan to sell the bike, it makes no sense to remove it. Just put it on the big chainring and leave it there. The presence of a derailleur costs you nothing.
If you use the chainrings you have, which are designed to be shiftable, you will find the chain comes off them quite easily if you are in the extreme ends of your rear gears. If you're riding on paved surfaces you can solve this by fitting a narrow-wide chainring instead: there are plenty of vendors including Absolute Black, SRAM and Race Face; I've used all of those and they work well.
As Alexander suggested you can stay with shiftable chainrings and use the front mech as a rudimentary chain-retention device. To do this you detach and remove the shifting cable and shifter then turn the lower limit screw until the mech is in the desired location. You can completely lock it in position using the upper limit screw as well if you like, but the lower limit screw and the spring should be enough. I wouldn't do it this way as you're unlikely to be able to use the full range of the cassette without the chain rubbing at the front. Maybe it's a good way to find out if you want to go to a single front ring before you pay for the proper chainring.