remove title of portfolio item

Hi there,

I create this page: http://www.bekijkhieruwnieuwewebsite.nl/stoere-keukens/
If the mouse remains on a portfolio item, the title of the item will appear.
See also screenshot: https://www.dropbox.com/s/bt3p501ctqfwbdl/Schermafbeelding%202020-05-13%20om%2009.15.27.png?dl=0
How can I remove it?

Thanks in advance.
Jeroen