In the following folder
/usr/share/lipstick-jolla-home-qt5/lockscreen/

Delete the following lines from Lockscreen.qml
ShowCalEvents
{
id: showcalevents
anchors
{
top: {
try {
weatherData.bottom
}
catch(e) {
networkNameAndDateLabels.bottom
}
}
topMargin: Theme.paddingMedium
right: parent.right
rightMargin: Theme.paddingMedium
}
}