Macbook Air - Trash problem

Hello there!

Since Big Sur was officially launched I updated my 2019 MBA.

Today I try to downgrade to Catalina, but anyway i change my decision again. So, I open my drive and from the application folder i found Catalina (it was around 7.5- 8 GB ot storage) and I delete it to the Trash. My problem is that now i can not delete it from there. it stay inside and I have any idea what to do. I am new one in Mac. I would like if someone can help me. Thanks in advance.

Here are the messages that it cames when i try delete Catalina.