Apps I will replace:
Firefox (replace with Brave Origin)
KMail (replace with Thunderbird)
Elisa (replace with VLC)
Apps I’ll just remove:
KMahjong and all other KGames
KWallet
What is your goal with removing them?
Try removing them with dnf one at a time.
You are likely to find that removing kwallet is not possible.
It is deeply built into kde plasma as the interface to storage of secrets like WiFi passwords etc.
What you can do is provide different backends to the be used by kwallet like keepassxc and in f45 it’s proposed to you oo7.
Removing just the kmail application will leave behind all the background services of akonadi.
In general it is safe, but you will need to check which dependancies are removed along with each. KDE links a lot of services, so you may find removing KDE programs remove all KDE programs.
Instead, install what you want and change the default software,eg browser in the system settings.
I usually install Fedora from the Everything installer. In the package selection screen, I select a custom operating system on the left and just KDE on the right, no KDE PIM, or KDE applications, or anything else. After the installation is finished, I can install the applications that I actually want (and I have Ansible playbooks to do that, so the whole installation takes like 30min to get in the state I want).
From your list, this leaves out Firefox, KMail, Elisa, and the KDE games (and also LibreOffice, unless you select it in the installer). It still includes KWallet, but, as @barryascott pointed out, this might be too deeply integrated, at least for now.
I have uninstalled all the apps you have mentioned with success and no issues. Even KWallet. I am a simple user though, I don’t know if they would break any functionality for someone who is a superuser or similar.
You are only removing the tip of the ice berg.
All the supporting libraries and services will still be installed and potential running in the background.
Is you intention to remove the apps from view? I think you have done this.
Or reduce the installed disk space? I think you are leaving a lot still installed.
Something else?
Well then maybe don’t have a myriad of things install and integrated by default. I didn’t need it nor want it so I deleted to the best of my abilities. Might not be the right move but puts my mind at ease so I’m okay 
Thanks for the explanation though.
Can i use Fedora Everything to just only install the KDE Plasma Desktop Environment without the pre-installed apps?
I just don’t want to have two of the same apps.
What about akonadi-server, can I remove that? Why is this even preinstalled?
I like having a more minimal set of apps when running KDE Plasma and, after installing Fedora KDE 44 with the Everything ISO, I remove the following in a tty (and then reboot) before logging in to Plasma for the first time.
sudo dnf5 group remove desktop-accessibility dial-up firefox guest-desktop-agents input-methods kde-apps kde-media kde-pim printing
sudo dnf rm abrt akonadi-server audiocd-kio ibus im-chooser kio-gdrive krdp krfb plasma-print-manager plasma-vault
sudo dnf in plasma-welcome-fedora
It is really important that before running such commands yourself, you run dnf5 group info $groupname and see what packages the group contains (and make a note of them). That way you are not struggling later with missing functionality and not knowing how to fix it by reinstalling a package. For example, the commands above will remove all printing functionality, which may not be useful/desirable for you.
I then install the KDE apps I want, without being tied to the package groups.
All of this apps is safe to remove if you check dependencies.
But don’t remove kwallet if you don’t install other wallet software.
For most user it means that kde plasma Just Works™.
For advanced users they can customise, as the OP and you are doing.