If your system is already installed and don’t want to reinstall it, you can edit the boot entry in the bootloader. In the bootloader, press Ctrl+e to edit the currently selected boot option, find the kernel line and add nomodeset at the end of the line. Finally, boot the system by pressing Ctrl+x. This modification will only apply to the current boot.
If you want to apply the boot modification permanently, edit /etc/default/grub, add nomodeset to line GRUB_CMDLINE_LINUX=, and then run: