Some people choose to remove the date from their WordPress blog posts for various reasons:

• Timeless Content: They want their content to appear evergreen and relevant regardless of when it was published. Without a date, readers are less likely to judge the content based on its age.
• Focus on Quality: Removing the date can shift the focus from when the content was published to the quality and relevance of the information itself.
• Consistency: If a blog covers topics that are not time-sensitive or regularly updated, removing dates can help maintain a consistent look and feel.
• Avoiding Outdated Perceptions: Posts with dates can sometimes give the impression that the content is outdated, especially if the date is several years old.
• Aesthetic Reasons: Some people prefer the cleaner look of their blog without the clutter of dates.

To change all posts date and time format, Go to Dashboard > Settings > General and find Date and Time Format settings.

• Custom Format  – In official PHP website you can find out all the date and time formats, Click here, Or by searching in google you can find date formats.