Think of having a tool-box of stopping skills. Every situation is different and may require a special stopping method! I know of people who can go on forever listing ways to stop. I'll list a few, from most common or most important to least common or "special." Learn the top ones first:

HEEL STOP: Bend knees, scissor skates, lift toe.

T-DRAG or L-DRAG: Drag a skate behind you.

TURN-STOP: Toes out, hug a huge cone.

STEP-STOP: Go slow, step in front.

UGLY SPEED SKATER STOP: Toes in, alternate legs...

GRASS STOP: Scissor glide into the grass.

TOE-WHEEL STOP: Like a T-Drag but just drag your toe-wheel. People who sell wheels like it when you do this one.

SLALOM STOP: Do successive, deep parallel turns until you slow enough to stop. requires a pretty wide area.

SNOWPLOW STOP: Apply outward and downward pressure to both heels so they smear or skid VERY slightly.

SWIZZLE STOP: As your legs come together, press forward.

HEEL STOP 2: Do a heel stop while up on your left toe wheel.

LUNGE STOP: Bend one knee WAY down, turn toward that knee.

REVERSE POWER SLIDE: Hockey stop with 90% of weight on non-sliding skate.

FULL POWER SLIDE: Do the above after a full 180 twist.

PORN STAR STOP: Like a T-Drag but your skidding skate is in front!

WHEEL-JAM STOP: Stop your left heel wheel by stepping on it with your right middle skate-wheels! Pete P. does this one!

KNEE STOP: Do a deep lunge and drag one knee-pad and toe on the ground!

PARALLEL LEAP STOP: Jump high, turn 90 degrees in the air, land hard while pushing back the way you came.

REAL HOCKEY STOP: Using rock-hard plastic wheels, find a gritty or sandy spot & slide sideways.

SPIN STOP: Like a turn stop but you go into a two-toe-wheel spin at the end.

Or how (NOT) to stop!

TREE OR POLE STOP: Skate past a pole, grab it as you go by with one outstretched arm, orbit a few times!

DOGGY-STYLE STOP: Fall on your wrist guards and knee-pads. Slide.

BUTT STOP: Fall on your butt. Slide to a stop. Whine.

TACKLE STOP: Skate into and hug any non-police officer.

SPANDEX STOP: Get lycra caught on a thorn as you skate by a plant. As lycra stretches you will slow down. Beware of backlash into thorn bush.

RADIATION STOP: Emit all of your kinetic energy in the form of photons. You will glow as you stop if you do it right.

TRIP STOP: Hit a rock that stops your gliding skate cold.

HELMET STOP: Rely on the energy absorption characteristics of a foam bicycle helmet. Aim at something rigid with your head down. Apply cervical collar.

ROAD-RASH STOP: Wear a helmet but no pads. As you fall, roll & slide randomly for full coverage.

PARKED CAR STOP: Self explanatory. Pick a cheap car.

CLIFF STOP: Do not worry, the fall will probably kill you before you actually stop.

I could go on forever. There are as many ways to stop as there are people. Invent your own!
DISCLAIMER: Some of the above stopping methods are silly! "It's a joke!" Do not attempt them or you may get hurt or worse, DIE! Take a lesson from a IISA/ICP-certified instructor