Assuming you mean whilst it's still a word, there are various ways:
Head
Bead
Beat
Boat
Boot
Foot
Head
Mead
Meat
Moat
Moot
Foot
rod
buck
grow, brew, or crew.
a leg
shave, stave, suave, slate...
Head is turned into tail by:HEALTEALTELLTALLTAIL
Some four letter words that can be made from the word 'quid' by changing one letter are:quadquitquiz
Sting
rod
buck
anew, knee, or know
grow, brew, or crew.
ANSWER tame wild
rearrange N and E and change the first letter.
a leg
long lone line wine wide
Mast(like on a ship) can become mask