I have a couple unique candle holders that I don't want to throw out, but there is candle wax at the bottom.
I found this amazing solution on Pinterest that showed me how to easily remove the remaining wax.
Simply boil some water,
and pour the hot water into your glass candle holders.
The wax will gradually rise to the top.
Once the wax at the top hardens a bit, you may want to cut it in half so it is easy to remove once cooled.
I would wait until the water and wax are completely cooled so you don't pour waxy water down your kitchen sink!
Remove the excess dirt with soap and water, and voilà!
You have a refurbished storage container that you can place a new candle in or use for another purpose.
Let me know if you decide to try this.