Use warm tap water and soap (if the molds have been used for soapmaking, simply soak in warm water for a half hour or so). Hot water, including dishwasher water, may warp the plastic.
The molds can tolerate wax and transparent soap temperatures of 135-145ºF. If you're concerned about warping, set the molds in a shallow cold-water bath for hot-temperature pours.
Please don't manhandle the molds when releasing contents! If you have any difficulties with soap or chocolate, place the molds in your freezer. For chocolate, a few minutes of freezer time will allow for easy unmolding. For soap, 1 hour should be sufficient.