Ubuntu 16.04LTS: Reset to 14.04LTS

It is not possible to perform a downgrade when using Ubuntu.

The only option is to perform a backup of all your personal data and to then perform a clean install of Ubuntu 14.04 LTS.

Ubuntu 14.04 LTS is supported until April 2019.

Hi Mark,
I am running multiboot on my system (Windows and parallel Ubuntu with lubuntu Desktop)
If I now do a clean install of Ubuntu 14.04 LTS as recommended, will this over-write the partition with Ubuntu 16.04 LTS
OR
must I first deinstall this? How do I do this without wiping off my Windows Operating System?

Ricky

When you perform the reinstall you will need to remove the current install then replace

I suggest you try a clean install of Xenial (16.04), I have personally never had a successful desktop Ubuntu upgrade from release to release.

OK, HOW do I uninstall the current install (sudo??) without wiping out my Windows Operating System (Multiboot)?

The actual problem is that after upgrade to 16.04 from14.04 LTS, my Lubuntu-Desktop has schrunk in size and therefore does not display everything. The page has to be scrolled from left to right (if a horizontal scroll bar is displayed at all, sometimes not) and from top to bottom!
My problem would be solved if I could enlarge the display to full screen, but this seems impossible? OR what must I do?

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Can anyone help:
a) How do I change Monitor resolution to a larger size (1280x768), than those offered in the screen properties (1024x768)?
b) How do I uninstall Lubuntu 16.04 LTS without wiping out Windows on a multi-boot System ? in order to do a clean install of Lubuntu 16.04 as proposed?

1. Try setting the screen resolution with cvt and randr commands
http://askubuntu.com/a/377944
https://wiki.ubuntu.com/X/Config/Resolution#Adding_undetected_resolutions

2. During the installation process you will be asked what partitioning scheme you want to use (use whole disk / install in parallel to the existing OS / something else)
If you select 'Something else' you get a partitioning tool where you can change or delete the existing partitions.
I recommend that you re-use the partitions that are currently used by the Ubuntu system for the new installation, and just format them again to delete the data (select formatting in the settings for the respective Linux partitions).
If you modify only the Ubuntu partitions and do not touch the Windows partitions, then this should leave the Windows system intact.
(Standard disclaimer for partitioning tools: Wrong selection or wrong action might cause data loss.)