First it is not a duplicate question as I already tested the solutions I found using a Google search. Here are what I tested:
https://github.com/dannyti/sboxsetup/wiki/Changing-OVH-Server-Kernel Switching from OVH kernel to default kernel without reinstalling Ubuntu
If it is really a duplicate please tell what I did wrong.
So I have an Armhf server from SoYouStart (OVh) which comes with a custom Linux Kernel:
uname -a
Linux ns3087832.ip-54-37-26.eu 4.9.124-armada375 #1 SMP Mon Sep 3 19:18:09 CEST 2018 armv7l GNU/Linux
The answers I found on the Internet suggest to install linux-image-generic and then change the grub config (removing 06_OVHkerne which I don't have). I did this but my server always boot with the custom kernel. Also grub wasn't installed so I installed.
Here some information that may help:
root@ubuntu /tmp [0|1]# ls -alh /boot/
total 44M
drwxr-xr-x 3 root root 4.0K Aug 14 15:12 .
drwxr-xr-x 22 root root 4.0K Jun 22 2020 ..
-rw-r--r-- 1 root root 1.4M Nov 15 2018 abi-4.15.0-42-generic
-rw-r--r-- 1 root root 226K Nov 15 2018 config-4.15.0-42-generic
-rw-r--r-- 1 root root 78K Sep 3 2018 config-4.9.124-armada375
drwxr-xr-x 5 root root 4.0K Aug 14 15:11 grub
-rw-r--r-- 1 root root 25M Aug 14 15:01 initrd.img-4.15.0-42-generic
-rw-r--r-- 1 root root 24 Nov 15 2018 retpoline-4.15.0-42-generic
-rw------- 1 root root 3.6M Nov 15 2018 System.map-4.15.0-42-generic
-rw------- 1 root root 1.7M Sep 3 2018 System.map-4.9.124-armada375
lrwxrwxrwx 1 root root 24 Sep 24 2018 uImage -> uImage-4.9.124-armada375
-rw------- 1 root root 4.5M Sep 3 2018 uImage-4.9.124-armada375
-rw------- 1 root root 7.9M Nov 15 2018 vmlinuz-4.15.0-42-generic
root@ubuntu /tmp# sfdisk -l /dev/sda
Disk /dev/sda: 5.47 TiB, 6001175126016 bytes, 11721045168 sectors
Disk model: HGST HUH728060AL
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: FF5C3324-73F8-4ED1-B452-14B5AF1CC4ED
Device Start End Sectors Size Type
/dev/sda1 40 2048 2009 1004.5K BIOS boot
/dev/sda2 4096 40962047 40957952 19.5G Linux filesystem
/dev/sda3 40962048 11719991295 11679029248 5.4T Linux filesystem
/dev/sda4 11719991296 11721037823 1046528 511M Linux swap
How can I change the Linux kernel of my server?
