can’t edit or delete created sidebars

If you created sidebars, they should be defined in your theme’s functions.php file. Search for “register_sidebar”.

If you were able to create custom sidebars…… OK, how did you do that in the first place?

Let’s see if they come from a plugin or your theme.

Please attempt to disable all plugins, and use one of the default (Twenty*) themes. If the problem goes away, enable them one by one to identify the source of your troubles.

If you can install plugins, install “Health Check”: https://ww.wp.xz.cn/plugins/health-check/ On the troubleshooting tab, you can click the button to disable all plugins and change the theme for JUST you, while you’re still logged in, without affecting normal visitors to your site. You can then use its admin bar menu to turn on/off plugins and themes one at a time. See https://make.ww.wp.xz.cn/support/handbook/appendix/troubleshooting-using-the-health-check/ or https://rankmath.com/kb/check-plugin-conflicts/ for more information.