converting from standard to compact crank
 

How many links should I remove to change from a 53-39 crank to a 50-34? Thanks.

As many as it takes to get the chain to the right length. There is no way to know if the chain was sized properly to begin with so removing a set number of links could leave you with a chain that is improperly sized.

you really don't need to remove any. while extra links mean a few grams extra weight, less tension in the drivetrain means less friction. I have a book by Eddie B from back in the 80s where he says that for time trials, his guys would make sure to have a little slack in the chain for the very reason of decreasing the load on the rear deraileur springs and thus decreasing friction loss in the drivetrain

so its up to you, but I never took any links out when I threw a compact on any of my bikes

as always, YMMV