Standard field customization
Key Takeaway
You can't delete a standard field or make it longer, but you can remove it from your page layouts. You can also customize parts of it, such as its picklist values and label.
Standard fields, such as Account Name on accounts, already exist on Salesforce objects, unlike custom fields, which you create to capture extra information. Customizing standard fields lets you fit the org to your business and keep the terms your users already know.
What you can't do with a standard field
If users don't need a standard field...
You can't delete a standard field, so remove it from your page layouts instead.
If you need a longer text area...
You can't increase the field length of a standard field, so consider creating a custom field.