T = readtable("https://www.mathworks.com/matlabcentral/answers/uploaded_files/1085695/flowrate_dates.xlsx", "Sheet", 3)
T = 365×11 table
Dates Flowrate_1 Flowrate_2 Flowrate_3 Flowrate_4 Flowrate_5 Flowrate_6 Flowrate_7 Flowrate_8 Flowrate_9 Flowrate_10
___________ __________ __________ __________ __________ __________ __________ __________ __________ __________ ___________
01-Apr-2020 100 100 100 100 100 100 100 100 100 100
02-Apr-2020 100 100 100 100 100 100 100 100 100 100
03-Apr-2020 100 100 100 100 100 100 100 100 100 100
04-Apr-2020 100 100 100 100 100 100 100 100 100 100
05-Apr-2020 100 100 100 100 100 100 100 100 100 100
06-Apr-2020 100 100 100 100 100 100 100 100 100 100
07-Apr-2020 100 100 100 100 100 100 100 100 100 100
08-Apr-2020 100 100 100 100 100 100 100 100 100 100
09-Apr-2020 100 100 100 100 100 100 100 100 100 100
10-Apr-2020 100 100 100 100 100 100 100 100 100 100
11-Apr-2020 100 100 100 100 100 100 100 100 100 100
12-Apr-2020 100 100 100 100 100 100 100 100 100 100
13-Apr-2020 100 100 100 100 100 100 100 100 100 100
14-Apr-2020 100 100 100 100 100 100 100 100 100 100
15-Apr-2020 100 100 100 100 100 100 100 100 100 100
16-Apr-2020 100 100 100 100 100 100 100 100 100 100
idx = T.Dates >= datetime('11/05/2020', 'InputFormat', 'dd/MM/yyyy') & ...
T.Dates <= datetime('28/09/2020', 'InputFormat', 'dd/MM/yyyy');
%T(idx, :) =[];
T.Flowrate_5(idx) = nan;
T(30:50,:)
ans = 21×11 table
Dates Flowrate_1 Flowrate_2 Flowrate_3 Flowrate_4 Flowrate_5 Flowrate_6 Flowrate_7 Flowrate_8 Flowrate_9 Flowrate_10
___________ __________ __________ __________ __________ __________ __________ __________ __________ __________ ___________
30-Apr-2020 100 100 100 100 100 100 100 100 100 100
01-May-2020 800 800 800 800 800 800 800 800 800 800
02-May-2020 800 800 800 800 800 800 800 800 800 800
03-May-2020 800 800 800 800 800 800 800 800 800 800
04-May-2020 800 800 800 800 800 800 800 800 800 800
05-May-2020 800 800 800 800 800 800 800 800 800 800
06-May-2020 800 800 800 800 800 800 800 800 800 800
07-May-2020 800 800 800 800 800 800 800 800 800 800
08-May-2020 800 800 800 800 800 800 800 800 800 800
09-May-2020 800 800 800 800 800 800 800 800 800 800
10-May-2020 800 800 800 800 800 800 800 800 800 800
11-May-2020 800 800 800 800 NaN 800 800 800 800 800
12-May-2020 800 800 800 800 NaN 800 800 800 800 800
13-May-2020 800 800 800 800 NaN 800 800 800 800 800
14-May-2020 800 800 800 800 NaN 800 800 800 800 800
15-May-2020 800 800 800 800 NaN 800 800 800 800 800