это то, что вы ищете?
import re
l=[]
list1 = ["a","b","c"]
sublist2=[]
list2=[re.sub("[0-9']+", '',i) for i in sublist2]
l.append(list1)
l.append(list2)
print(l)
#result:[['a', 'b', 'c'], []]
import re
l=[]
list1 = ["a","b","c"]
sublist2=["1","3","f"]
list2=[re.sub("[0-9']+", '',i) for i in sublist2]
l.append(list1)
l.append(list2)
print(l)
#result:[['a', 'b', 'c'], ['', '', 'f']]