Sure, here are the steps:
You can list the currently installed kernels using rpm:
$ rpm -q kernel-core
kernel-core-5.6.8-300.fc32.x86_64
kernel-core-5.6.10-300.fc32.x86_64
kernel-core-5.6.11-300.fc32.x86_64
Then, you can remove one (not the one currently in use which you can find by running uname -a in a terminal) using dnf:
$ sudo dnf remove kernel-core-5.6.8-300.fc32
Dependencies resolved.
==============================================================================================================================================================================================================================================
Package Architecture Version Repository Size
==============================================================================================================================================================================================================================================
Removing:
kernel-core x86_64 5.6.8-300.fc32 @updates-testing 72 M
Removing dependent packages:
kernel x86_64 5.6.8-300.fc32 @updates-testing 0
kernel-modules x86_64 5.6.8-300.fc32 @updates-testing 28 M
kernel-modules-extra x86_64 5.6.8-300.fc32 @updates-testing 1.9 M
Transaction Summary
==============================================================================================================================================================================================================================================
Remove 4 Packages
Freed space: 102 M
Is this ok [y/N]:
To only ever have two kernels installed, you need to change the value of installonly_limit in /etc/dnf/dnf.conf. It is 3 by default:
$ cat /etc/dnf/dnf.conf
[main]
gpgcheck=1
installonly_limit=3
clean_requirements_on_remove=True
best=False
skip_if_unavailable=True
You can do this using a terminal editor: nano/peco/vi/vim/emacs or sed:
$ sudo sed -i 's/installonly_limit=3/installonly_limit=2/' /etc/dnf/dnf.conf
$ cat /etc/dnf/dnf.conf
[main]
gpgcheck=1
installonly_limit=2
clean_requirements_on_remove=True
best=False
skip_if_unavailable=True