You can delete it by doing :
sudo userdel -r postgres

Then go ahead with:

alps install libreoffice

No I tried that already several times it says user does not exist

Oh. I am extremely sorry! Its my mistake, I gave you the wrong command. The correct command is:

sudo groupdel postgres

make[2]: Leaving directory '/var/cache/alps/sources/postgresql-9.5.1/doc/src'
make[1]: Leaving directory '/var/cache/alps/sources/postgresql-9.5.1/doc'
install -v -dm700 /srv/pgsql/data &&
install -v -dm755 /run/postgresql &&
groupadd -g 41 postgres &&
useradd -c "PostgreSQL Server" -g postgres -d /srv/pgsql/data \
-u 41 postgres &&
chown -Rv postgresostgres /srv/pgsql /run/postgresql &&
su - postgres -c '/usr/bin/initdb -D /srv/pgsql/data'

install: creating directory '/srv/pgsql/data'
install: creating directory '/run/postgresql'
changed ownership of '/srv/pgsql/data' from root:root to postgresostgres
ownership of '/srv/pgsql' retained as postgresostgres
changed ownership of '/run/postgresql' from root:root to postgresostgres
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.

initdb: invalid locale settings; check LANG and LC_* environment variables
Error occured in execution of /var/cache/alps/scripts/postgresql.sh
Aborting
username [ ~ ]$ locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_US.utf
LC_CTYPE="en_US.utf"
LC_NUMERIC="en_US.utf"
LC_TIME="en_US.utf"
LC_COLLATE="en_US.utf"
LC_MONETARY="en_US.utf"
LC_MESSAGES="en_US.utf"
LC_PAPER="en_US.utf"
LC_NAME="en_US.utf"
LC_ADDRESS="en_US.utf"
LC_TELEPHONE="en_US.utf"
LC_MEASUREMENT="en_US.utf"
LC_IDENTIFICATION="en_US.utf"
LC_ALL=

Try setting the locale this way:

export LC_CTYPE=en_US.UTF-8

Then delete the user/group again because it got created.

sudo userdel -r postgres

And retry

And I am not sure if the locale is correctly set in your case. Should it not be en_US.utf8 instead of just en_US.utf?

Yes that was the problem but now I have

Enter language : en
ln: failed to create symbolic link 'external/tarballs/libreoffice-dictionaries-5.1.0.3.tar.xz': File exists
ln: failed to create symbolic link 'external/tarballs/libreoffice-translations-5.1.0.3.tar.xz': File exists
Error occured in execution of /var/cache/alps/scripts/libreoffice.sh
Aborting

That is simple. Just delete the old libreoffice untarred directories and you are good to go:

sudo rm -r /var/cache/alps/sources/libreoffice-5.1.0.3/

and then retry

this solved the problem.

but there are other things such as nothing happens when I type alps clean and very important it will not open folder with open as administrator even though Gksu is installed. This can be seen from preferences.

OK. I will check that and get back.