Anglicanism is a church tradition, just like Presbyterianism and Baptist. The Church of England and the Episcopalian church are national denominations in the Anglican tradition. In general we don't use tags for individual denominations, so I think they should be merged into anglicanism.
Episcopal technically means a church with bishops, but the only question tagged with it is about the Episcopalian church, so it's more of a tag typo. As there is already a tag for bishops we don't need to keep it.