Systemd – How to Remove Options from Unit Files Without Overriding

How are lines removed from a standard (system) systemd unit file? Here are the details:

ls -la /etc/ssh/ssh_host_*key*

This shows I have unused and unwanted host key types. They are not configured in my sshd_config, but I prefer they not exist at all. If I remove them, they get auto-regenerated.

From what I see, /usr/lib/systemd/system/sshd.service includes:

Wants=sshdgenkeys.service

The contents of that are shown below with cat /usr/lib/systemd/system/sshdgenkeys.service:

[Unit]
Description=SSH Key Generation
ConditionPathExists=|!/etc/ssh/ssh_host_dsa_key
ConditionPathExists=|!/etc/ssh/ssh_host_dsa_key.pub
ConditionPathExists=|!/etc/ssh/ssh_host_ecdsa_key
ConditionPathExists=|!/etc/ssh/ssh_host_ecdsa_key.pub
ConditionPathExists=|!/etc/ssh/ssh_host_ed25519_key
ConditionPathExists=|!/etc/ssh/ssh_host_ed25519_key.pub
ConditionPathExists=|!/etc/ssh/ssh_host_rsa_key
ConditionPathExists=|!/etc/ssh/ssh_host_rsa_key.pub

[Service]
ExecStart=/usr/bin/ssh-keygen -A
Type=oneshot
RemainAfterExit=yes

I know I can override or create a unit file setting using systemctl edit, but how are lines like ConditionPathExists=|!/etc/ssh/ssh_host_dsa_key removed?

What I want to end up with is similar to this:

[Unit]
Description=SSH Key Generation
ConditionPathExists=|!/etc/ssh/ssh_host_ed25519_key
ConditionPathExists=|!/etc/ssh/ssh_host_ed25519_key.pub
ConditionPathExists=|!/etc/ssh/ssh_host_rsa_key
ConditionPathExists=|!/etc/ssh/ssh_host_rsa_key.pub

[Service]
ExecStart=/usr/bin/ssh-keygen -t rsa|ed25519 -a 32
Type=oneshot
RemainAfterExit=yes

I'm not sure that command is correct for ssh-keygen, but that's the general idea. I only want to generate two host key types, not all.