How reset RTC on ESP32?

If I turn ESP32 off and on, the RTC timer will be cleared. How can I delete it in software?
I want to reset: rtc_time_slowclk_to_us(rtc_time_get(), esp_clk_slowclk_cal_get());

Does it have a backup battery?

You want to set the CPU's cycle counter back to 0?

The ESP32 has a nano-second cycle counter which is used to derive other timings. The ESP32's API uses esp_restart to reset the cycle counter. Miscellaneous System APIs - ESP32 - — ESP-IDF Programming Guide latest documentation (espressif.com)