$ sudo apt-get remove --purge mysql-server*
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'mysql-server-core-5.0' for regex 'mysql-server*'
Note, selecting 'mysql-server-core-5.1' for regex 'mysql-server*'
Note, selecting 'mysql-server-core-5.5' for regex 'mysql-server*'
Note, selecting 'mysql-server-core-5.6' for regex 'mysql-server*'
Note, selecting 'mysql-server-5.0' for regex 'mysql-server*'
Note, selecting 'mysql-server-5.1' for regex 'mysql-server*'
Note, selecting 'mysql-server-5.5' for regex 'mysql-server*'
Note, selecting 'mysql-server-5.6' for regex 'mysql-server*'
Note, selecting 'virtual-mysql-server-core' for regex 'mysql-server*'
Note, selecting 'mysql-server' for regex 'mysql-server*'
Note, selecting 'mysql-server-core' for regex 'mysql-server*'
Note, selecting 'virtual-mysql-server' for regex 'mysql-server*'
Package 'mysql-server-5.1' is not installed, so not removed
Package 'mysql-server-core-5.1' is not installed, so not removed
Package 'mysql-server-5.0' is not installed, so not removed
Package 'mysql-server-core-5.0' is not installed, so not removed
Note, selecting 'mysql-server-core-5.5' instead of 'mysql-server-core'
Package 'mysql-server-core-5.6' is not installed, so not removed
The following packages were automatically installed and are no longer required:
  libav-tools libavdevice53 libavfilter3 libavresample1 libbs2b0 libctemplate2
  libdbd-mysql-perl libdbi-perl libgtkmm-2.4-1c2a liblua5.1-0 libmpg123-0
  libmysqlclient18 libpcrecpp0 libquvi-scripts libquvi7 libterm-readkey-perl
  libtinyxml2.6.2 libupstart1 libvdpau1 libzip2 linux-headers-3.16.0-30
  linux-headers-3.16.0-30-generic linux-image-3.16.0-30-generic
  linux-image-extra-3.16.0-30-generic mplayer2 mysql-client-5.5
  mysql-client-core-5.5 mysql-common python-pysqlite2 rtmpdump
Use 'apt-get autoremove' to remove them.
The following packages will be REMOVED:
  mysql-server* mysql-server-5.5* mysql-server-5.6* mysql-server-core-5.5*
0 upgraded, 0 newly installed, 4 to remove and 21 not upgraded.
2 not fully installed or removed.
After this operation, 52.7 MB disk space will be freed.
Do you want to continue? [Y/n] yes
(Reading database ... 290607 files and directories currently installed.)
Removing mysql-server (5.5.43-0ubuntu0.14.04.1) ...
Removing mysql-server-5.5 (5.5.43-0ubuntu0.14.04.1) ...
Purging configuration files for mysql-server-5.5 (5.5.43-0ubuntu0.14.04.1) ...
Removing mysql-server-5.6 (5.6.19-0ubuntu0.14.04.1) ...
Purging configuration files for mysql-server-5.6 (5.6.19-0ubuntu0.14.04.1) ...
Removing mysql-server-core-5.5 (5.5.43-0ubuntu0.14.04.1) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...