You have to remove product-size-chart.liquid code from product template. If you don't have coding knowledge you need to hire a Shopify expert. If you'd like to discuss this more, don't hesitate to send me a PM.
If my reply helpful then please Like to let me know! If my answered is right according to your question, Mark it as an Accepted Solution. Facing more issues ?Hire me For Quick Chat: Say hello in WhatsApp : +8801761469797
You deleted the size-chart file from a theme, which resulted in an error. If you don't want to utilise the size chart, you don't need to remove any theme files—you can just disable it in the customisation settings or engage a developer to assist you in doing so.