1x Conversion FC-T8000
A simple 1x conversion would only need a new narrow wide chainring (and probably shorter chainring bolts).  Narrow wide chainrings in 104BCD (which is the required size for the model you list) are available from USD10 if you order a cheap chain ring directly from China.  You can continue to use the crankset you have, as well as all other components.  After you installed the new chain ring you remove your front derailleur, the shifter cable and your left hand shifter and you're done.
if you make sure it's a narrow wide chainring (or some other shape that is designed for 1x) for most riding you would likely not need a chain keeper (although it doesn't hurt to have one).  The shape of these chainrings will make sure the chain doesn't drop to the left or right of the chainring.
For more &quot;complicated&quot; 1x conversations you would want to review your gearing after loosing 2 chainrings.  In that case you would need a new cassette and potentially a new rear derailleur depending on the new cassette.  However you mentioned your intention is to simplify the bike while being happy with the current gearing (seeing you never shift the front derailleur).