Either cut it, or cold turkey. Make them disappear and suffer thru a few days?
My daughter was an addict! But from about 16 months it was ONLY exclusively for bed. Nap and night time and from 22 mos on she was in a toddler bed and knew if her feet were on the floor and that "Dowdy" (her name for it) was in her mouth, it went into the trash..no second chances. We didn't buy any more...but had a zillion of them.
We had her all worked up and built up that on the day she turned 3, all the last few Dowdy's were going in the trash. She knew it and was not fighting it. I was a nanny then and when we she got up (at home) she tossed her Dowdy..no biggie. When we got to work, I mentioned it and she went right to her nap room (their spare bedroom off the laundry room...like a housekeepers room)..and tossed the one in there! She napped great that day...and slept great at home that night! Lots of talk about hows shes 3 now..a big girl..all of that . She still had her Blankie and her Flip Kitty (white beanie baby cat).
The next day, when nap time at work rolled around, she says "Momma...I have my Horsey Blankie and my Flip Kitty...but I need my Dowdy now". I said "No, remember you are 3..a big girl" She said "But my birthday is all gone now...I need my Dowdy's back."
OMG...no wonder she did it so easy! She thought it was just one day..just ON her birthday. Craptastic! The next 2 or 3 days were a slight bit of hell...she was just sooo sad. Heartbroken-like. But like I said, she was also addicted to her Blankie and beanie kitty, so she survived just fine. She still sleeps with the fragile see thru thin Blankie under her pillow. The Beanie kitty was put away for safekeeping a few years ago..she is fragile now too. She will turn 17 at the end of summer! Thank goodness shes not into drugs or smoking...her addictive nature showed up early!
Working with daycare kids all these years I find its easiest to have them gone or just for naps by about 8/9 mos old...naps I don't care for a long time...but not out of the bed. By 2 yrs old I want them gone totally and I always accomplish this by just making them disappear here and there till they are just gone (even if parents let them have them alot at home)
Good Luck!