object collections in sims 4

[jonquil79]

I am playing my second household in sims 4 and some of the household collections (inc aliens and fish) have carried over from my previous game but I wanted to start with a clean slate and have the challenge of collecting everything again. How do I avoid this? 

Also, how do you get a fossil slide? Its an option with the microscope but it doesn't highlight because I cant figure out how to collect one?!