Hi

Decimation to lower the sampling rate is straightforward if wanted,
just by taking one sample out of every N.

You'll need a decimation filter to keep aliases out if the original signal
has spectral components that are above the decimated Fs/2 (Nyquist!).
One way to accomplish this is to feed the original signal into the circular
buffer of a FIR filter of suitable design, at the original Fs, and then
compute the filter output at the decimated output Fs.

73
Johan SM6LKM