Just very slowly. I hope this is a legitimate Rx? That would be a bit easier if you can get your doctor's cooperation, but even if you have been buying it illegally, there's no reason you can't go to a pain specialist for help coming off it with a real Rx. There's no reason you should have withdrawal symptoms. Get a pill cutter and start with taking 3/4 of the dose for a couple of weeks. Then go to half for a couple of weeks. Finally to 1/4 and then none. (Talk to the pharmacist about whether there is a form that is easiest to cut--there may be different shapes of the generic version that are easier.) Don't feel you have to rush--it could be 3 weeks at a time if nec. If you are taking it for actual pain, you should consult with a pain specialist to find other measures you can take, or possible non-narcotic meds. I find that taking opiates for real pain results in no longer feeling high from it. If you do get a lift from it, you may have to think about how you will feel when that boost is all gone. This is where it would be nice to have some moral support from someone. I spoke to my doctor and he did not offer anything more than "Go ahead and just reduce it gradually." I was disappointed, but I feel that I can do it. It's just harder to have resolve on those days when there is more pain, since the pain fluctuates.
If you have aches and pains, use a hot tub or hot baths.There are some supplements that might help if you have side effects. One discussion of this is as part of the so-called Thomas recipe, https://www.drugs.com/forum/featured-conditions/thomas-recipe-opiate-withdrawal-treatment-35169.html
The biggest predictor of success will be your determination, so it helps to find motivational things to read, even make yourself some affirmation cards with AA-type sayings ("One day at a time," "I can do this," etc.), someone to talk to. Imagine what it would feel like if you were not dependent on any drug and just could experience a normal joy of life that is naturally there. I mean literally visualize it, try to imagine how it would feel, because that's how you move toward a goal, by having an image in your mind of what it is.