@truten maybe you can search the file with this command "sudo find / -name uninstall.sh"

or you can try to make a new file in the path with "touch uninstall.sh", edit the file with "nano uninstall.sh", and paste below contents to the file by right-click, the content is copied from my uninstall.sh fil:

.

#!/bin/bash
NAME="omada"
DESC="Omada Controller"

DEST_DIR=/opt/tplink
DEST_FOLDER=EAPController
INSTALLDIR=${DEST_DIR}/${DEST_FOLDER}
#INSTALLDIR=$(dirname $(readlink -f $0))
LINK=/etc/init.d/tpeap
LINK_CMD=/usr/bin/tpeap

MAIN_CLASS="com.tp_link.eap.start.EapLinuxMain"

#Define the variable to judge that if
#the execution of uninstall.sh is for upgrading.
UNINSTALL_TYPE=$1

user_confirm() {
    if [ "${UNINSTALL_TYPE}" == "upgrade" ]; then
               return 0
    fi
    while true
    do
        echo -n "${DESC} will be uninstalled from [${INSTALLDIR}] (y/n): "
        read input
        confirm=`echo $input | tr '[a-z]' '[A-Z]'`

        if [ "$confirm" == "Y" -o "$confirm" == "YES" ]; then
               return 0
        elif [ "$confirm" == "N" -o "$confirm" == "NO" ]; then
               return 1
        fi
    done
}

user_keep_db() {
    if [ "${UNINSTALL_TYPE}" == "upgrade" ]; then
               return 0
    fi
    while true
    do
        echo -n "Do you want to backup database [${INSTALLDIR}/data/db] (y/n): "
        read input
        confirm=`echo $input | tr '[a-z]' '[A-Z]'`

        if [ "$confirm" == "Y" -o "$confirm" == "YES" ]; then
               return 0
        elif [ "$confirm" == "N" -o "$confirm" == "NO" ]; then
               return 1
        fi
    done
}

# return: 0, exist; 1, not exist;
link_exist() {
        if test -x $1; then
                if [ ${INSTALLDIR}/bin/control.sh = $(readlink -f $1) ]; then
                        return 0
                fi
        fi

        return 1
}

# return: 1,running; 0, not running;
is_running() {
    [ -z "$(pgrep -f ${MAIN_CLASS})" ] && {
        return 0
    }

    return 1
}

# root permission check
check_perms() {
        [ $(id -ru) != 0 ] && { echo "You must be root to uninstall the ${DESC}. Exit." 1>&2; exit 1; }
}

# root permission check
check_perms

# user confirm
if ! user_confirm; then
    exit
fi

NEED_KEEP_DB=0

if ! user_keep_db; then
    NEED_KEEP_DB=0
else
    NEED_KEEP_DB=1
fi

echo "========================"
echo "Uninstallation start ..."

link_exist ${LINK}
exist=$?
count=0
while [ $exist -eq 1 ]
do
    count=`expr ${count} + 1`
    link_exist ${LINK}${count}
    exist=$?
    if [ $count -gt 100 ]; then
                # not found LINK
                break;
    fi
done

for i in `seq 1 3` ; do
    is_running
    [ 0 == $? ] && {
        break
    }

    echo "${DESC} is running, going to stop it."
    if [ -x ${INSTALLDIR}/bin/control.sh ]; then
        ${INSTALLDIR}/bin/control.sh stop
    else
            echo "Can't stop ${DESC}! You should stop it by yourself before uninstall."
            exit
    fi

    sleep 3
done

# removing
if [ $count -eq 0 ]; then
    link_name=${LINK}
    link_cmd_name=${LINK_CMD}
else
    link_name=${LINK}${count}
    link_cmd_name=${LINK_CMD}${count}
fi

update-rc.d $(basename ${link_name}) remove 2>/dev/null
result=$?
if [ $result -ne 0 ]; then
    chkconfig --del ${link_name}
    chkconfig --del ${link_cmd_name}
fi

rm ${link_name}
rm ${link_cmd_name}

BACKUP_FOLDER=${INSTALLDIR}/../eap_db_backup
DB_FILE_NAME=eap.db.tar.gz
MAP_FILE_NAME=eap.map.tar.gz

if [ $NEED_KEEP_DB == 1 ]; then
    mkdir $BACKUP_FOLDER > /dev/null 2>&1
    cd ${INSTALLDIR}/data
    tar zcvf $DB_FILE_NAME db
    cp -f $DB_FILE_NAME $BACKUP_FOLDER/

    #backup map
    tar zcvf $MAP_FILE_NAME map
    cp -f $MAP_FILE_NAME $BACKUP_FOLDER/
fi

rm -rf ${INSTALLDIR}

echo "Uninstall ${DESC} successfully."
 

In case anyone needs, I found a solution that worked for me (ubuntu 16.04):

 

remove omada package (it will remove dependencies as well, you may also need to run with --purge option):

dpkg -r omada

 

list the packages (ensure omada package is not there):

dpkg-query -l | less

 

install the new package:
dpkg -i omada_v4.2.8_linux_x64.deb

 

install all dependencies:

sudo apt-get -f install