how to delete W-4 since I entered the form by mistake

Are you referring to a W-2? If so, the best way to rectify this to delete the form.

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Here's the general procedure for viewing the forms list and deleting unwanted forms, schedules, and worksheets in TurboTax Online:

1. Open or continue your return in TurboTax.
2. In the left menu, select Tax Tools and then Tools.
3. In the pop-up window Tool Center, choose Delete a form.
4. Select Delete next to the form/schedule/worksheet in the list and follow the instructions.

I need to delete the W-4 Form and start over due to a mistake   It does not allow me to correct previous entries.

A W-4 is a form you give to your employer to have taxes withheld from your pay.  I think you really mean a W-2.