In CRM you can show only Date part of date time attribute, but not only time.
To show only date part of date time attribute, you need to go field customization and change Format as Date.
Modifying CRM form HTML (DOM) is not supported, so I will go with web resource.
1. Add HTML web resource on your form.
2. Set HTML web resource properties like, Number of rows, scrolling border, formatting etc.
3. Add web resource on your form, This HTML web resource should be look like attribute on Form, so set properties accordingly.
4. Add Jquery latest library in your entity form libraries.
5. Add Following code into you HTML web resource.
2. Hide your date field on form.
3. Save and publish customization.