canvas js. How to clear the canvas?

Question

Canvas

When the button is clicked, a curved line is drawn in the canvas.
How to make it so that when the button is pressed again, the canvas is cleared and the line is drawn again

HTML


JS

let canvas = document.getElementById("cnvs")
let ctx = canvas.getContext('2d');
let LengthLinii = (rand * 100) * 1.5;
let linRelomlenia = LengthLinii / 2;
let visotaGrafika = 300 - ((rand * 100) * 1.5);

ctx.moveTo(0, 280);
ctx.strokeStyle = "#bc9109";
ctx.linewidth = 5;
ctx.shadowColor = "#bc9109";
ctx.shadowOffsetX = 30;
ctx.shadowOffsetY = 60;
ctx.shadowblur = 80;
ctx.quadraticCurveTo(linRelomlenia, 270, DlinaLinii, visotaGrafika)
ctx.stroke();