There are many ways to remove the post date of all word press, have alot of wordpress plugins, but i prefer to add this code in CSS section, post date will disappear in all the posts,
1. Change the Permalinks,
Navigate to Settings > Permalinks
in Common Settings tab, select Post Name ( /%postname%/ )
2. Navigate to Appearance > Customize > and then at the left bottom of customize page, click Additional CSS
add this code :
.entry-meta .entry-date.published {
display: none;
}
if not, then try this code
.entry-meta {
display: none;
}
We believe that one of the above code will work to remove the date in post.