Use the rikaichan popup dictionary or your favorite reference tool with my transcription below the photo if you need help reading this sign. In addition to the lone kanji character, you’ll notice that there’s a katakana character as well as hiragana.
Katakana is often used in place of kanji or hiragana for emphasis, and that’s just what it does here at the very end and in a colloquial way that takes the edge off the fact that we’re being told not to do something.
The numbers below refer to the kanji I’ve transcribed below the photo, and correspond to their order of appearance in both Heisig’s Remembering the Kanji and Kanji in Context.
To learn more about how this information can help you learn kanji, please read this.
Kanji In Context(KIC32)