replacing crank shaft seal question

can i just pull the crank out with a puller, from the outside??? or do i have to open up the head and replace the seal internally?? i always get mixed answers when i asked a couple of techs, was wondering if anyone has done this repair before? i’ve been putting it off for a long time now, i’m gonna have to do it when i get my ride back, my engine bay is disgusting.

thanks for the help in advance