First put on your gloves, as the lye might still be active, and unmould your soap.
You can check the pH of your soap with a pH meter or pH strips, however the strips are not always reliable.
In the soap makers’ world you will hear of the zap test. The zap test is when you touch the soap with the tip of your tongue and if you get a light zap like from a 9 volt battery then there is still unsaponified lye in your soap. If your soap has gelled, then it shouldn’t zap after 24 hours. If it hasn’t gelled it might zap up to 3 days.
If your soap zaps after 4 days then it might have too much lye in it (lye heavy) due to an incorrect formula or incorrect weighing of ingredients, so it might be unusable. If you have the formula and can recalculate the quantities, you can add the missing ingredients and re-batch it.
If the soap doesn’t zap you can slice it in individual bars and let them to cure. To cut the soap you can use a knife, a soap cutter (straight as in the picture above or crinkled) or a wire cutter (soap or cheese cutter).