There is no quick, easy and safe way.

You essentially need a distillation set-up (a “still”), like a moonshiner. You’re goal would be distill lower alcohol concentrations over to higher concentrations over the course of many hours.

Of course your still, even if legal where you live, would need to be carefully constructed to avoid things like lead solder.

You’d also need to be trained to avoid an explosion or a fire.

Also, you’d need some equipment to help you figure out what was happening, since both water and ethanol are clear liquids.

Just buy concentrated alcohol or cheap overproof vodka from your local shop. Cheaper, faster, much safer and legal.