I want to delete the stored file while updating it?

My file uploaded perfectly but the problem is the old will remain in the storage folder, how to delete it while updating my file?

storage path is like that

/storage/uploads/php pdo.pdf

my controller

  public function storeFile(Request $request , $id) {

        $request->validate([
            'acc_status'            => 'required',
           'acc_document'          => 'required|mimes:doc,docx,pdf,txt,zip|max:2000',
        ],[
                    'acc_document.required' => 'Please upload a file',
                    'acc_document.mimes' => 'Only doc,docx,pdf,txt and zip are allowed',
                    'acc_document.max' => 'Sorry! Maximum allowed size for an image is 5MB',
        ]);
            $requisition = Requisition::find($id);
            $requisition->acc_status =  $request->get('acc_status');

             if($request->hasFile('acc_document')){
            $FileName =  $request->file('acc_document')->getClientOriginalName();
            $path = $request->file('acc_document')->storeAs('uploads', $FileName , 'public');
            $requisition->acc_document = '/storage/' . $path; }
            $requisition->save();
            //$requisition->update($request->all());

        return redirect()->route('requisition.index')
            ->with('success', 'Account document has been uploaded successfully.');
     }