[Urgent] There's no cancel subscription button.

Hi, I just found out that about 3 months ago, I accidentally subscribed a very awful app called "Ever Color". Since I discovered that half of my balance just blew out, and I can't take my money back for thing that I purchased three months ago, I tried to cancel the subscription. However, it seems like there is no cancel subscription button unlike any other apps. The option only follows with a content "ever color plus (1 week)", but without any cancelling button. The policy says that it "automatically renews until cancelled. To stop, tap cancel subscription in settings before next billing date." Please help me out as soon as possible because I feel extremely distraught over my money slipping through this idiot app. Thank you.