If you have R21018a or later, use the lowpass function. (Also see the links in and at the end of that documentation page.)
It is also easy to design your own filter:
Fs = 11025; % Sampling Frequency
Fn = Fs/2;
Wp = 1000/Fn; % Passband Frequency (Normalised)
Ws = 1010/Fn; % Stopband Frequency (Normalised)
Rp = 1; % Passband Ripple
Rs = 60; % Passband Ripple (Attenuation)
[n,Wp] = ellipord(Wp,Ws,Rp,Rs); % Elliptic Order Calculation
[z,p,k] = ellip(n,Rp,Rs,Wp); % Elliptic Filter Design: Zero-Pole-Gain
[sos,g] = zp2sos(z,p,k); % Second-Order Section For Stability
figure
freqz(sos, 2^16, Fs) % Filter Bode Plot
signal_filt = filtfilt(sos, g, signal); % Filter Signal
