RE: O.S. .46 AX Replacement Bearings - remove shields?
As it related to seals, the decision is a bit more complex...
It is only in regards to the front bearing.
If your front bearing is a grease-packed, double sealed one that is capable of running at the engine's intended RPM range (grease-packed bearings are more RPM limited, compared to open/shielded bearings), just leave both seals in.
Don't remove the rear seal, since the bearing does not need the engine's lubricant to run.
It is greased for life.
As to RPM limits; with oil-spray lubrication, an R6-Z/ZZ/open bearing can run at 36,000 RPM.
If grease-packed, the limiting RPM is reduced to 29,000 RPM and with contact-seals (friction), this number is reduced even further, to only 20,000 RPM.
For the RPM range of the OS.46AX, none of these limits apply, since it will never be run at over 17,000 RPM; even if spinning a toothpick prop...