Delete form boxes from PDF

Hi There,

I have created an excel spreadsheet which creates a front page for a document with names etc.

One of the columns is a blank column for the signer to add a tick to say it has been completed (not textbox) though when its is exported to a PDF and I go to add a tick using Fill & Sign, it creates a little text field in the empty cell so it wont let me add the tick.

Can anyone help with this?