A third option: You can add and remove perks via console commands (if you're playing on a PC):
I'll put this in spoiler tags, just in case console commands are not kosher in the general forum - my apologies to the mods if this is the case. Just cut them out of the post if necessary.
Console method to add and remove perks inside spoiler tags. Note this can be used to cheat, don't read if you're weak willed!
Spoiler ~ to access the console
help "Perkname" 4
this will return, amongst other stuff: PERK (
) "Perkname". You want the Perknumber. For example typing:
help "Novice Destruction" 4
returns:
PERK (000F2CA8) "Novice Destruction"
then, you can use player.addperk Perknumber and player.removeperk Perknumber to add and remove perks, so follouwing our Novice Destruction example above:
player.removeperk 000F2CA8
will remove the Novice Destrucion perk.
Note that removing perks will NOT give you perk points back, you will need to player.addperk to "move" your perk points into new perks.
That all said, really, don't sweat some oddly placed perks. As a rule of thumb, they're pretty much always useful. My character, for example, has an odd smattering of points in the early magic schools, despite rarely ever using magic. However, it's EXTREMELY handy to have those low level spells cast at 1/2 magika. Likewise, while I don't wear heavy armour, should I put on a single piece due to it's awesome enchants, I've got one perk in the entry level Heavy Armor tree to help boost it's effectiveness.
Rarely will you have perks that are actually useless, and you get a LOT of perks overall.