My parents won't let me practice guitar...?

Whenever I start practicing guitar, my parents will start yelling at me within like 2 minutes saying things like go do your homework or go study or go practice piano/violin. 2 b honest, piano and violin aren't fun for me, partly because my parents are always telling me to practice them, and partly because I'm rly sick of playing the same pieces over and over. It really frustrates me that I can’t ever improve because my parents don’t let me play. I rly want to get better and also it’s just rly fun and relaxing and like a break from schoolwork…how can I get my parents 2 let me practice in peace?