您可以将文件的内存Map到出现在内存中的文件的内容，然后将内存从第2行开始移动到文件的开头。然后将文件截断为新文件长度。
对于70GB的文件来说，这可能不会太快。它仍然需要将文件更改刷新回磁盘。这只是文件的工作方式，但它不需要额外的70GB磁盘空间，如编写新文件和删除旧文件的常规过程。

import mmap

# Create test file for demonstration (about 50MB)
#
# The quick brown fox jumped over 1 lazy dogs
# The quick brown fox jumped over 2 lazy dogs
# ...
# The quick brown fox jumped over 1,000,000 lazy dogs

with open('test.txt', 'w') as f:
    for i in range(1, 1_000_001):
        print(f'The quick brown fox jumped over {i:,} lazy dogs', file=f)

# Create memory-mapped file, read first line, shift file memory
# starting from offset of the 2nd line back to the beginning of the file.
# This removes the first line.
with open('test.txt', 'r+b') as f:
    with mmap.mmap(f.fileno(), 0) as mm:
        size = mm.size()
        line = mm.readline()
        linelen = len(line)
        mm.move(0, linelen, size - linelen)
        mm.flush()

    # Truncate the file to the shorter length.
    f.truncate(size - linelen)

# Read the first line of the new file.
with open('test.txt') as f:
    print(f.readline())

输出：

The quick brown fox jumped over 2 lazy dogs

不幸的是，它是不可能立即删除它，但uou可以尝试这个代码。这将基本上重写同一文件中的内容，除了第一行：

import fileinput

with fileinput.input(files=('text.txt'), inplace=True) as f:
    for line_number, line in enumerate(f):
       if line_number == 0:
           continue
       print(line, end='')

inplace=True参数告诉Python修改文件，而不是创建一个新文件。