A warm bearing ( 250F ) will slide on a properly machined shaft at room temperature.
Same rule for dropping a bearing in a housing.
( Use the EASA tables for calculating the machining tolerances, these numbers are the motor and gear box industry standard )
There are a variety of different ways to remove a seal, most involve prying or driving out from the other side.
You can tap them in with a hammer, or warm up the housing and press them in usually with a drill press on small jobs like this.
Never beat on the inner race to drive in a bearing ( into a housing or the reverse for a shaft ).
Just one hit can cause Brinnelling ( dents in the race inner or outer ) and the life of the bearing can be greatly reduced.