Can we access historical data for inactive or delisted coins via CoinGecko API?

No, you will not be able to access historical data for inactive or delisted coins via the CoinGecko API.

There are several reasons why a coin is deactivated:

• The coin is a potential honeypot
• The coin infringes the trademarks or IPs of others
• The coin is requested to be delisted by the project team
• The coin is deactivated automatically when no trading activity is detected for 30 days