Try this —
T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1085430/kpmarch.xlsx')
T1 = 744×6 table
OBSR_YMD A_VALUE OBSRVT_NM K_VALUE CRT_DT OBSR_VYMD
_______________________ _______ __________________ _______ ______________ __________________
{'2022-03-31 21:00:00'} {'27'} {'Planetary' } {'2'} {'2022-04-30'} {'20220331210000'}
{'2022-03-31 21:00:00'} {'18'} {'Fredericksburg'} {'2'} {'2022-04-30'} {'20220331210000'}
{'2022-03-31 21:00:00'} {'35'} {'College' } {'2'} {'2022-04-30'} {'20220331210000'}
{'2022-03-31 18:00:00'} {'27'} {'Planetary' } {'4'} {'2022-04-30'} {'20220331180000'}
{'2022-03-31 18:00:00'} {'18'} {'Fredericksburg'} {'3'} {'2022-04-30'} {'20220331180000'}
{'2022-03-31 18:00:00'} {'35'} {'College' } {'4'} {'2022-04-30'} {'20220331180000'}
{'2022-03-31 15:00:00'} {'27'} {'Planetary' } {'4'} {'2022-04-30'} {'20220331150000'}
{'2022-03-31 15:00:00'} {'18'} {'Fredericksburg'} {'4'} {'2022-04-30'} {'20220331150000'}
{'2022-03-31 15:00:00'} {'35'} {'College' } {'4'} {'2022-04-30'} {'20220331150000'}
{'2022-03-31 12:00:00'} {'27'} {'Planetary' } {'4'} {'2022-04-30'} {'20220331120000'}
{'2022-03-31 12:00:00'} {'18'} {'Fredericksburg'} {'3'} {'2022-04-30'} {'20220331120000'}
{'2022-03-31 12:00:00'} {'35'} {'College' } {'6'} {'2022-04-30'} {'20220331120000'}
{'2022-03-31 09:00:00'} {'27'} {'Planetary' } {'4'} {'2022-04-30'} {'20220331090000'}
{'2022-03-31 09:00:00'} {'18'} {'Fredericksburg'} {'3'} {'2022-04-30'} {'20220331090000'}
{'2022-03-31 09:00:00'} {'35'} {'College' } {'5'} {'2022-04-30'} {'20220331090000'}
{'2022-03-31 06:00:00'} {'27'} {'Planetary' } {'5'} {'2022-04-30'} {'20220331060000'}
Lv = ismember(T1{:,3},'Planetary');
Result = T1(Lv,[1 3 4])
Result = 248×3 table
OBSR_YMD OBSRVT_NM K_VALUE
_______________________ _____________ _______
{'2022-03-31 21:00:00'} {'Planetary'} {'2'}
{'2022-03-31 18:00:00'} {'Planetary'} {'4'}
{'2022-03-31 15:00:00'} {'Planetary'} {'4'}
{'2022-03-31 12:00:00'} {'Planetary'} {'4'}
{'2022-03-31 09:00:00'} {'Planetary'} {'4'}
{'2022-03-31 06:00:00'} {'Planetary'} {'5'}
{'2022-03-31 03:00:00'} {'Planetary'} {'5'}
{'2022-03-31 00:00:00'} {'Planetary'} {'4'}
{'2022-03-30 21:00:00'} {'Planetary'} {'2'}
{'2022-03-30 18:00:00'} {'Planetary'} {'2'}
{'2022-03-30 15:00:00'} {'Planetary'} {'1'}
{'2022-03-30 12:00:00'} {'Planetary'} {'2'}
{'2022-03-30 09:00:00'} {'Planetary'} {'1'}
{'2022-03-30 06:00:00'} {'Planetary'} {'1'}
{'2022-03-30 03:00:00'} {'Planetary'} {'1'}
{'2022-03-30 00:00:00'} {'Planetary'} {'2'}
There are likely also other approaches.
.