WordPress: Disable add custom field

I allow a guest to post on my WordPress site. I disabled some fields, but I let the user select only one field.

Cool, but he can edit this field. Example: Field: name. After I a开发者_如何学编程dded it, he can rename the field to name2.

So, how do I can a disable this?

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Use the readonly attribute,

<input type="text" name="test" value="<?php echo $name ?>" readonly="readonly">