Is there a way to remove all tags from an entity?

Of course there's also the way of manually inputting all tags that you want to remove and tagging yourself for removal of all Tags to remove all tags that you want to remove before removing the tag of removal of tags functioning as basically a clear tag

Basically:

tag @p add removeTags

then, a Repeating command block detects if any player has a tag and also has the tag of removal

tag @a[tag=removeTag] remove Tag1
tag @a[tag=removeTag] remove Tag2
tag @a[tag=removeTag] remove Tag3
tag @a[tag=removeTag] remove removeTag

in a chain command block

It's not possible. For entities you could set their Tags NBT tag to be an empty list, but you can't modify NBT of players. The tag command doesn't allow wildcards for tags, only for entities.