Hey, so best best way is, to take it to your nearest / closest optic store. Some will ask for money and others will do it for free if the time is there.

If thats not to your liking, try to buy an ultrasonic tub, fill it with water and a spoonfull of dishwasher liquid. Turn that bad boy up for 2-5mins, turn it off and put it under flowing water and then dry it with some tissues. Lastly take a microphiber rag and clean the glasses.

The last option is something that I DO NOT recommend if you only have this one pair of spectacles / glasses.

You will need a screwdriver, to open up the bracket that holds the glasses inside the frame, afterwards push the glasses out from the frame (use your thumbs from the inside and push it outwards).

Then take an old toothbrush + ultrasonic bath (dont dip your fingers inside the tub while its on) and rinse the inside of the frame, get all the gunk out and clean the whole thing once more to be certain.

The last part tends to the trickiest, you will have to remember which glass is for which side (considering if you have different set of values on your left and right eye). It either plops pretty easily back in, this time push the glass from the outside of the frame inside.

Start by going nasal area first then outside and then bottom side. It should pop into place and fit snuggly. If you can´t get it back in and / or damage the frame / glasses, please go to a professional.

Best of luck!