There isn't an agreement on this...some remove the inner seal on install, some don't. Certainly the seal will not prevent moisture from getting INto the bearing. The idea is, once it gets in, you might as well make it easy to get out by removing the seal.
BTW, a mechanics scribe worked around the inside diameter of the seal with flick it right out.
Try it on the outside diameter and you'll likely ruin it.
As mentioned, don't remove the bearings for a re-grease. No reason to stress the hub more than you have to. It's a steel race and an aluminum hub! Especially with the 'pound it out' method you're giving the aluminum hell every time you change bearings.
Yeah, you can get replacement bearings for $5. And then you'll be replacing them again in a few months.
CBR has a bearing 'kit' that comes with seals...runs around $45 or so. Lifetime guaranteed! No, that doesn't mean they don't wear out, but they'll last one heckuva lot longer than some all-balls chinese/korean junk.
That's my personal experience anyway.
When they DO wear out, CBR won't gripe about replacement, either!