Can't find installed kernel and make older kernel as default kernel

I use Linux 5.4.0 LTS in Ubuntu. Now I installed a new kernel Linux 5.6.7 stable using these commands

sudo make modules_installsudo make install

Now my default kernel is Linux 5.6.7. After installing the kernel I couldn't find the kernel in directory. It does not show in terminal too. When run the command,

dpkg --list | grep linux-image

The new kernel was not in the list.

ii  linux-image-5.4.0-26-generic               5.4.0-26.30                                amd64        Signed kernel image genericii  linux-image-generic                        5.4.0.26.32                                amd64        Generic Linux kernel image

These header installed where C header installed. Can I make Linux 5.6.7 an image like Linux 5.4.0 and bring it in /usr/src/kernels?

Linux 5.6.7 is now default kernel for booting. How can I make Linux 5.4.0 as my default kernel for booting?

As Linux 5.6.7 is not in dpkg list the command sudo apt remove linux-kernel. How can I remove if I want to remove it?