If you are admitting that you are infringing on copyright then we will ask you to either take the page down or we will have to suspend your account. Additionally, we will have to refund all transactions associated with the sale of the infringing content.
You can avoid issues (generally) by not using copyright characters in your projects. Often those who want to reference a copyrighted character without infringing on it will use a parody or something that shares some qualities but is not that character. For example, instead of Shrek you may have a green ogre of different appearance named Shrak.
Under DMCA we generally do not police content for copyright violation, we assume all uploaders are respecting the rights of others. Only when we receive a report do with go through the DMCA process outlined here: https://itch.io/docs/legal/terms#6-digital-millennium-copyright-act
Since you are admitting to violating copyright outright though, (and on a public forum!) then we do not need any additional evidence to see that you are violating our terms of service and thus your account will be suspended if you do not fix the page.