My MTB has currently a Deore FC-617 2x crankset. I am looking what components I need to convert to 1x. Do I need to change the crankset, or simply getting a new chainring for my existing crankset will work fine ?
The problem going x1 from x2 is the chain line can end up being wrong. Its easier with an x3, you just use the middle position and can often get away with using the standard chain ring. With a 2x conversion you use spacers to get the chain ring into the correct position Refer Here, which usually required longer chain ring bolts than standard on a 2x.
The M786 has a derailleur is less than ideal for going to 1x unless you plan to stick to an 11-36 cassette. Although many run it with 40 or 42 tooth cassettes, its max tooth size specification is 36 teeth. You can use third party adapters to increase its useful maximum tooth size at a cost. If you already need a new cassette and derailleur to go 1x, the extra cost of a shifter and chain means going 11 speed will give a much better system for only a little extra cost.