does anyone know how to do with this??
Take the computer to a technical support and ask to format it to install an Operating System of your choice
Take the computer to a technical support
Well, that useless advice aside, you just need to create an installer USB and boot from it, then install the OS you want.
IDK what exactly your PC is, but the general procedure for this is to first make a bootable USB with the OS you need. If you want Windows, then you will need access to a Windows PC. Linux does not really work that well for creating windows installers, it’s pretty hard. Once you have access to a PC with Windows, you need to grab the Windows Download Tool here - https://www.microsoft.com/en-us/software-download/windows10. Run that, then insert a usb stick you don’t mind wiping (you will lose all data on the flash drive). Then select to install for another PC, select to write iso to usb drive, then point the tool to your usb. It will write the installer to the usb. Then you can take it out, and go to your Endless PC. Shut it down, put in the usb, then press the key to access boot options while it shows the manufacturer splash screen. You will need to look up the key for this, it varies depending on the model. Sometimes the PC will tell you what key you need to press for boot options. In the boot select screen, select your USB drive. The Windows installer will boot. Select custom install, then delete all the partitions on the drive. Create a new one, select it, then press next. The installer will run through setup, and once finished, you will reboot into your new windows os.
If you just want another Linux distro that doesn’t have a broken package manager, then you can use only Endless, without another PC. Just grab the Appimage for balena etcher here - https://www.balena.io/etcher/ , save it to the laptop, and run it. Also download the iso for your Linux distro. Now, same procedure, flash iso to usb, boot from it, run through the installer.
Thanks for your explanation on this topic. The answer from @LeandroStanger was fully correct, because supporting the installation of other operating systems except Endless OS is out of scope for this board here.
As for your later comment on the “broken package manager”. It’s not broken, it is as it is by design. Even if classical package management works most of the time, it has its own inherent problems which may be solved partially by new technologies like OSTree and Flatpak. If you take the huge amount of EOS users worldwide in perspective to the ones who post here their issues, you will notice that for most users the EOS way of distribution the OS and Applications works.
For Power Users there are always fallback solutions which provides means for installing applications not available as Flatpak.