Have anyone installed and uninstalled Deepin 23 in a dual boot setup yet?

I would like to try out Deepin 23. Because I only have one PC at this moment, I need to do so in the dual boot setup. I experienced the difficulty of removing Deepin (the dual boot script) in a dual boot for Deepin 20.X. I need to make sure that I can remove Deepin 23 from a dual boot easily before installing it. Otherwise, I will use another distro such as Zorin.

There's no need to "uninstall" an installation before installing another. All competent Linux installers allow to replace an existing installation with some other. The method depends on the installer. You may need or wish to make its first steps remove an installation and/or its partitions in order to create new ones. Better ones simply allow to specify which existing partitions/filesystems to use for which purpose on the new installation.

I am more considering the boot script than the partition.

Which "boot script"? What is a "dual boot script"? All my PCs are multiboot (none have as few as two operating systems), and have been for close to three decades, so none have "dual boot" anything. What exactly was the difficulty in removing the old Deepin?

If you are installing for UEFI mode, scripts are a non-issue as to boot control. The Grub script called depends on the firmware priority. A new installation will normally make itself top priority. The old ESP disk entry can be removed by anything capable of file deletion from a VFAT filesystem. The firmware entry can be removed by BIOS reconfiguration or using efibootmgr. UEFI doesn't boot via MBR code. There is no code in a GPT disk's MBR, only the partition table. The grub.cfg script on the old installation will disappear in same manner as the rest of the installation, either reformat of existing old partition, or delete the partition it's on.

Following the instruction on https://wiki.deepin.org/en/Installat...stall%20deepin, I couldn't see the Deepin within EasyUEFI. I am unable to follow the second option.

The "Uninstall Linux on deepin" #1 instruction there is formatted so as to make it impossible to succeed unless you're experienced enough to not need any such instruction.needs to read:However, that instruction only is applicable if your Windows and Deepin are installed in legacy/MBR mode. You've provided no information to suggest whether or not that is the state of your system. For most computers made in the past 10 or so years, that situation is uncommon. If Deepin is still bootable, boot it, run the command sudo efibootmgr, and show here the result. If it's not, enter BIOS setup and examine the boot priorities section and try to determine whether UEFI entries exist, or both UEFI and legacy/MBR/CSM entries exist, or only legacy/MBR/CSM entries exist, then describe here what you find. Optionally, boot Windows and try to find where Windows reports whether UEFI is in use or not.

For removal with UEFI the current state, the instructions for removal via Deepin are incomplete on that page.

As I explained in my first reply, "uninstalling" Deepin as preparation in order to install some other Linux distro is entirely unnecessary.