hide "add" linkbutton when i click to "edit" linkbutton"

Question

hi ,

this is my site form 

 

 

and when i click to edit link button the add link button visible

 

 

this is my form code 

 

 <asp:TemplateField  HeaderStyle-Width="50px">

    <ItemTemplate>
 <asp:LinkButton ID="link_edit" runat="server" CommandName="edit" ToolTip="edit" Text="<span class='table-icons'><i class='fas fa-edit'></i></span>" style="width:20px"></asp:LinkButton>

 <asp:LinkButton ID="link_delete" runat="server" CommandName="delete" ToolTip="delete" Text="<span class='table-icons'><i class='fas fa-times'></i></span>" style="width:20px;" OnClientClick="return confirm('Are you sure you want to delete this record?');"></asp:LinkButton>

  </ItemTemplate>

 <EditItemTemplate>
<asp:LinkButton ID="link_update" runat="server" CommandName="Update" ToolTip="Update" Text="<span class='table-icons'><i class='far fa-save'></i></span>" style="width:20px;"></asp:LinkButton>

<asp:LinkButton ID="link_cancel" runat="server" CommandName="Cancel" ToolTip="cancel" Text="<span class='table-icons'><i class='fas fa-times'></i></span>" style="width:20px;"></asp:LinkButton>

</EditItemTemplate>


<HeaderTemplate>

 <label style="color: #3366FF">Action</label>
<asp:LinkButton ID="link_add" runat="server" ValidationGroup="company_country" CausesValidation="true" CommandName="addnew" ToolTip="addnew" Text="<span class='table-icons' style='font-size:15pt;'><i class='far fa-save'></i></span>"></asp:LinkButton>

 </HeaderTemplate>

 </asp:TemplateField>

 and this is my function that i would define invisible = false 

protected void GridView_cause_RowEditing(object sender, GridViewEditEventArgs e)
        {
            GridView_cause.EditIndex = e.NewEditIndex;
            PARAM_CAUSE_DEPARTURE_DAO cause = new PARAM_CAUSE_DEPARTURE_DAO(this._sSqlConnectionString);
            display_cause();
            cause.edit(GridView_cause);
            display_cause_form();
        }

 help me please