Remove that create button


I have set up 3 level of approval in material request:
Where the material request will be approved by the manager first and then approved by accountant and then by CEO.
MaterIal Request>Appproval by Manager>Approval byAccountant> Approval by CEO

But when the accountant has approved the Material Request ,there is a button create which enables me to create Purchase order.
Can you suggest me what should i do to remove that create button ,preventing me from creating Purchase order.

It is only when the CEO approves that material requsest ,then i will need that create button to create Purchase order.

@trishty_thakoor you need handle this in js code to display the button only for some particular conditions.