How can I find the site of the pet treasure, where it is possible to remove the items?

Hover on the personal dropdown at the top of the page, then hover on pets where it shows your list of pets. There are two links for each pet, you click on the one that says "pet" and you're brought to a new page of options, one of which is "Edit Treasure" click that and on that page there is a small X in the top right corner of each item, click the X to remove them.

Alternatively, hover on the personal dropdown at the top of the page, and click on the Pets option, where you are brought to this page: https://subeta.net/pets.php . On this page there is a small downward pointing arrow in the top right corner of the box that has the pet's hunger, happiness, etc - click that arrow. In that dropdown there is a link to their Treasure which also shows how many spaces you're using out of the total. You can also edit the treasure at this link.

I was trying first the personal dropdown menu, which did not work for me, because none of the links seem to be in function right now. But it worked for me to go over the sidebar "pets" and then your second discription. Thank you so much for your help. ❤