Delete some words with PHP from textarea

How could I do that, in the text ready in a text box, I draw some words? J & # 39; explains:

I have a form where textarea contains the following text:

Please note that I bring the name, company and date of admission to the comic strip. Until here everything is fine, but I want to give the administrator the freedom to change the text and save it as a template.

For this, I thought about getting the information from the database, erasing the information from the database and replacing it with _________.

But how would I do this in PHP, based on the principle below:

connection, $ idColaborator);
$ sql = mysqli_query ($ this-> connection, "SELECT * FROM tb_colaborator WHERE IdColaborator =". $ idColaborator. ";");
$ display = mysqli_fetch_object ($ sql);
// I stopped here