我认为您正在寻找:

Drop[Ss,{t},{t}]  

时间:

ClearAll["Global`*"];

First@Timing[a = RandomInteger[1000, {5000, 5000}];]
0.34

First@Timing[Drop[a, {2}, {2}]]
0.11

而

First@Timing[Transpose@Delete[Transpose@Delete[a, 2], 2]]
0.5