Debian – Dovecot “Address already in use” error

I've some problem with starting dovecot server. I get the following error:

Failed to start Dovecot :
Error: service(imap-login): listen(*, 143) failed: Address already in use
Error: service(imap-login): listen(::, 143) failed: Address already in use
Error: service(imap-login): listen(*, 993) failed: Address already in use
Error: service(imap-login): listen(::, 993) failed: Address already in use
Fatal: Failed to start listeners

So I run netstat command for 993 port:

# netstat -lnp | grep 993
tcp        0      0 0.0.0.0:993             0.0.0.0:*               LISTEN      1/init          
tcp6       0      0 :::993                  :::*                    LISTEN      1/init

What can I do to stop init process listening on these ports?

EDIT

Result of systemctl -all list-sockets command:

# systemctl -all list-sockets
LISTEN                          UNIT                            ACTIVATES
/run/acpid.socket               acpid.socket                    acpid.service
/run/dmeventd-client            dm-event.socket                 dm-event.service
/run/dmeventd-server            dm-event.socket                 dm-event.service
/run/lvm/lvmetad.socket         lvm2-lvmetad.socket             lvm2-lvmetad.service
/run/systemd/initctl/fifo       systemd-initctl.socket          systemd-initctl.service
/run/systemd/journal/dev-log    systemd-journald-dev-log.socket systemd-journald.service
/run/systemd/journal/socket     systemd-journald.socket         systemd-journald.service
/run/systemd/journal/stdout     systemd-journald.socket         systemd-journald.service
/run/systemd/journal/syslog     syslog.socket                   rsyslog.service
/run/systemd/shutdownd          systemd-shutdownd.socket        systemd-shutdownd.service
/run/udev/control               systemd-udevd-control.socket    systemd-udevd.service
/var/run/clamav/clamd.ctl       clamav-daemon.socket            clamav-daemon.service
/var/run/dbus/system_bus_socket dbus.socket                     dbus.service
0.0.0.0:143                     dovecot.socket                  dovecot.service
0.0.0.0:993                     dovecot.socket                  dovecot.service
[::]:143                        dovecot.socket                  dovecot.service
[::]:993                        dovecot.socket                  dovecot.service
kobject-uevent 1                systemd-udevd-kernel.socket     systemd-udevd.service
18 sockets listed.